diff --git a/.gitignore b/.gitignore
index 94360a7..9961cb8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,6 +2,8 @@
 composer.lock
 .env
 .phpunit.result.cache
+CLAUDE.md
+AGENTS.md
 /coverage/
 .idea/
 .vscode/
diff --git a/MILESTONES.md b/MILESTONES.md
index cab0e69..e5a5a27 100644
--- a/MILESTONES.md
+++ b/MILESTONES.md
@@ -4,11 +4,11 @@ This document outlines the phased development roadmap for the Atlas Routing engi
 
 ## Milestone 1: Foundation & Core Architecture
 *Goal: Establish the base classes, configuration handling, and the internal route representation.*
-- [ ] Define `Route` and `RouteDefinition` classes (SRP focused).
-- [ ] Implement the `Router` class with Inversion of Control (DI for config).
-- [ ] Create `Config` object to handle `modules_path`, `routes_file`, and `modules_glob`.
-- [ ] Implement `MissingConfigurationException`.
-- [ ] Setup Basic PHPUnit suite with a "Hello World" route test.
+- [x] Define `Route` and `RouteDefinition` classes (SRP focused).
+- [x] Implement the `Router` class with Inversion of Control (DI for config).
+- [x] Create `Config` object to handle `modules_path`, `routes_file`, and `modules_glob`.
+- [x] Implement `MissingConfigurationException`.
+- [x] Setup Basic PHPUnit suite with a "Hello World" route test.
 
 ## Milestone 2: Basic URI Matching & Methods
 *Goal: Implement the matching engine for standard HTTP methods and static URIs.*
diff --git a/src/Config.php b/src/Config.php
new file mode 100644
index 0000000..c54d01d
--- /dev/null
+++ b/src/Config.php
@@ -0,0 +1,85 @@
+<?php
+
+namespace Atlas;
+
+use ArrayAccess;
+use IteratorAggregate;
+
+class Config implements ArrayAccess, IteratorAggregate
+{
+    public function __construct(
+        private readonly array $options
+    ) {}
+
+    public function get(string $key, mixed $default = null): mixed
+    {
+        return $this->options[$key] ?? $default;
+    }
+
+    public function has(string $key): bool
+    {
+        return isset($this->options[$key]);
+    }
+
+    public function getModulesPath(): array|string|null
+    {
+        $modulesPath = $this->get('modules_path');
+
+        if ($modulesPath === null) {
+            return null;
+        }
+
+        return is_array($modulesPath) ? $modulesPath : [$modulesPath];
+    }
+
+    public function getRoutesFile(): string
+    {
+        return $this->get('routes_file', 'routes.php');
+    }
+
+    public function getModulesGlob(): string|null
+    {
+        return $this->get('modules_glob');
+    }
+
+    public function getModulesPathList(): array
+    {
+        $modulesPath = $this->getModulesPath();
+
+        if ($modulesPath === null) {
+            return [];
+        }
+
+        return is_array($modulesPath) ? $modulesPath : [$modulesPath];
+    }
+
+    public function toArray(): array
+    {
+        return $this->options;
+    }
+
+    public function offsetExists(mixed $offset): bool
+    {
+        return isset($this->options[$offset]);
+    }
+
+    public function offsetGet(mixed $offset): mixed
+    {
+        return $this->options[$offset] ?? null;
+    }
+
+    public function offsetSet(mixed $offset, mixed $value): void
+    {
+        $this->options[$offset] = $value;
+    }
+
+    public function offsetUnset(mixed $offset): void
+    {
+        unset($this->options[$offset]);
+    }
+
+    public function getIterator(): \Traversable
+    {
+        return new \ArrayIterator($this->options);
+    }
+}
\ No newline at end of file
diff --git a/src/MissingConfigurationException.php b/src/MissingConfigurationException.php
new file mode 100644
index 0000000..9658f92
--- /dev/null
+++ b/src/MissingConfigurationException.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Atlas;
+
+class MissingConfigurationException extends \RuntimeException
+{
+}
\ No newline at end of file
diff --git a/src/Route.php b/src/Route.php
new file mode 100644
index 0000000..e738bad
--- /dev/null
+++ b/src/Route.php
@@ -0,0 +1,29 @@
+<?php
+
+namespace Atlas;
+
+use Psr\Http\Message\ServerRequestInterface;
+
+final class Route
+{
+    public function __construct(
+        private readonly string $method,
+        private readonly string $path,
+        private readonly string|callable $handler
+    ) {}
+
+    public function getMethod(): string
+    {
+        return $this->method;
+    }
+
+    public function getPath(): string
+    {
+        return $this->path;
+    }
+
+    public function getHandler(): string|callable
+    {
+        return $this->handler;
+    }
+}
\ No newline at end of file
diff --git a/src/RouteDefinition.php b/src/RouteDefinition.php
new file mode 100644
index 0000000..1086204
--- /dev/null
+++ b/src/RouteDefinition.php
@@ -0,0 +1,82 @@
+<?php
+
+namespace Atlas;
+
+use Psr\Http\Message\UriInterface;
+
+final class RouteDefinition
+{
+    public function __construct(
+        private readonly string $method,
+        private readonly string $pattern,
+        private readonly string $path,
+        private readonly mixed $handler,
+        private readonly string|null $name = null,
+        private readonly array $middleware = [],
+        private readonly array $validation = [],
+        private readonly array $defaults = [],
+        private readonly string|null $module = null,
+        private readonly array $attributes = []
+    ) {}
+
+    public function getMethod(): string
+    {
+        return $this->method;
+    }
+
+    public function getPath(): string
+    {
+        return $this->path;
+    }
+
+    public function getHandler(): string|callable
+    {
+        return $this->handler;
+    }
+
+    public function getName(): ?string
+    {
+        return $this->name;
+    }
+
+    public function getMiddleware(): array
+    {
+        return $this->middleware;
+    }
+
+    public function getValidation(): array
+    {
+        return $this->validation;
+    }
+
+    public function getDefaults(): array
+    {
+        return $this->defaults;
+    }
+
+    public function getModule(): ?string
+    {
+        return $this->module;
+    }
+
+    public function getAttributes(): array
+    {
+        return $this->attributes;
+    }
+
+    public function toArray(): array
+    {
+        return [
+            'method' => $this->method,
+            'pattern' => $this->pattern,
+            'path' => $this->path,
+            'handler' => $this->handler,
+            'name' => $this->name,
+            'middleware' => $this->middleware,
+            'validation' => $this->validation,
+            'defaults' => $this->defaults,
+            'module' => $this->module,
+            'attributes' => $this->attributes
+        ];
+    }
+}
\ No newline at end of file
diff --git a/src/RouteGroup.php b/src/RouteGroup.php
new file mode 100644
index 0000000..41d9690
--- /dev/null
+++ b/src/RouteGroup.php
@@ -0,0 +1,70 @@
+<?php
+
+namespace Atlas;
+
+class RouteGroup
+{
+    public function __construct(
+        private array $options = [],
+        private readonly Router $router = null
+    ) {}
+
+    public static function create(array $options, Router $router): self
+    {
+        $self = new self($options);
+        $self->router = $router;
+        return $self;
+    }
+
+    public function get(string $path, string|callable $handler, string|null $name = null): self
+    {
+        $fullPath = $this->buildFullPath($path);
+        return $this->router ? $this->router->get($fullPath, $handler, $name) : $this;
+    }
+
+    public function post(string $path, string|callable $handler, string|null $name = null): self
+    {
+        $fullPath = $this->buildFullPath($path);
+        return $this->router ? $this->router->post($fullPath, $handler, $name) : $this;
+    }
+
+    public function put(string $path, string|callable $handler, string|null $name = null): self
+    {
+        $fullPath = $this->buildFullPath($path);
+        return $this->router ? $this->router->put($fullPath, $handler, $name) : $this;
+    }
+
+    public function patch(string $path, string|callable $handler, string|null $name = null): self
+    {
+        $fullPath = $this->buildFullPath($path);
+        return $this->router ? $this->router->patch($fullPath, $handler, $name) : $this;
+    }
+
+    public function delete(string $path, string|callable $handler, string|null $name = null): self
+    {
+        $fullPath = $this->buildFullPath($path);
+        return $this->router ? $this->router->delete($fullPath, $handler, $name) : $this;
+    }
+
+    private function buildFullPath(string $path): string
+    {
+        $prefix = $this->options['prefix'] ?? '';
+
+        if (empty($prefix)) {
+            return $path;
+        }
+
+        return rtrim($prefix, '/') . '/' . ltrim($path, '/');
+    }
+
+    public function setOption(string $key, mixed $value): self
+    {
+        $this->options[$key] = $value;
+        return $this;
+    }
+
+    public function getOptions(): array
+    {
+        return $this->options;
+    }
+}
\ No newline at end of file
diff --git a/src/RouteNotFoundException.php b/src/RouteNotFoundException.php
new file mode 100644
index 0000000..6a0a690
--- /dev/null
+++ b/src/RouteNotFoundException.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Atlas;
+
+class RouteNotFoundException extends \RuntimeException
+{
+}
\ No newline at end of file
diff --git a/src/RouteValidationException.php b/src/RouteValidationException.php
new file mode 100644
index 0000000..a9e9bf6
--- /dev/null
+++ b/src/RouteValidationException.php
@@ -0,0 +1,7 @@
+<?php
+
+namespace Atlas;
+
+class RouteValidationException extends \RuntimeException
+{
+}
\ No newline at end of file
diff --git a/src/Router.php b/src/Router.php
new file mode 100644
index 0000000..0434e15
--- /dev/null
+++ b/src/Router.php
@@ -0,0 +1,173 @@
+<?php
+
+namespace Atlas;
+
+use Psr\Http\Message\ServerRequestInterface;
+
+class Router
+{
+    private array $routes = [];
+
+    public function __construct(
+        private readonly Config $config
+    ) {}
+
+    public function get(string $path, string|callable $handler, string|null $name = null): self
+    {
+        $this->registerRoute('GET', $path, $handler, $name);
+        return $this;
+    }
+
+    public function post(string $path, string|callable $handler, string|null $name = null): self
+    {
+        $this->registerRoute('POST', $path, $handler, $name);
+        return $this;
+    }
+
+    public function put(string $path, string|callable $handler, string|null $name = null): self
+    {
+        $this->registerRoute('PUT', $path, $handler, $name);
+        return $this;
+    }
+
+    public function patch(string $path, string|callable $handler, string|null $name = null): self
+    {
+        $this->registerRoute('PATCH', $path, $handler, $name);
+        return $this;
+    }
+
+    public function delete(string $path, string|callable $handler, string|null $name = null): self
+    {
+        $this->registerRoute('DELETE', $path, $handler, $name);
+        return $this;
+    }
+
+    private function registerRoute(string $method, string $path, mixed $handler, string|null $name = null): void
+    {
+        $routeDefinition = new RouteDefinition(
+            $method,
+            $this->normalizePath($path),
+            $this->normalizePath($path),
+            $handler,
+            $name
+        );
+
+        $this->storeRoute($routeDefinition);
+    }
+
+    private function normalizePath(string $path): string
+    {
+        return '/' . ltrim($path, '/');
+    }
+
+    protected function storeRoute(RouteDefinition $routeDefinition): void
+    {
+        // Routes will be managed by a route collection class (to be implemented)
+        // For now, we register them in an array property
+        if (!isset($this->routes)) {
+            $this->routes = [];
+        }
+
+        $this->routes[] = $routeDefinition;
+    }
+
+    public function getRoutes(): iterable
+    {
+        return $this->routes ?? [];
+    }
+
+    public function match(ServerRequestInterface $request): RouteDefinition|null
+    {
+        $method = strtoupper($request->getMethod());
+        $path = $this->normalizePath($request->getUri()->getPath());
+
+        foreach ($this->getRoutes() as $routeDefinition) {
+            if (strtoupper($routeDefinition->getMethod()) === $method && $routeDefinition->getPath() === $path) {
+                return $routeDefinition;
+            }
+        }
+
+        return null;
+    }
+
+    public function url(string $name, array $parameters = []): string
+    {
+        $routes = $this->getRoutes();
+        $foundRoute = null;
+
+        foreach ($routes as $routeDefinition) {
+            if ($routeDefinition->getName() === $name) {
+                $foundRoute = $routeDefinition;
+                break;
+            }
+        }
+
+        if ($foundRoute === null) {
+            throw new RouteNotFoundException(sprintf('Route "%s" not found for URL generation', $name));
+        }
+
+        $path = $foundRoute->getPath();
+        $path = $this->replaceParameters($path, $parameters);
+
+        return $path;
+    }
+
+    private function replaceParameters(string $path, array $parameters): string
+    {
+        foreach ($parameters as $key => $value) {
+            $pattern = '{{' . $key . '}}';
+            $path = str_replace($pattern, $value, $path);
+        }
+
+        return $path;
+    }
+
+    public function group(array $options): RouteGroup
+    {
+        return new RouteGroup($options, $this);
+    }
+
+    public function module(string|array $identifier): self
+    {
+        $identifier = is_string($identifier) ? [$identifier] : $identifier;
+
+        $modulesPath = $this->config->getModulesPath();
+        $routesFile = $this->config->getRoutesFile();
+
+        if ($modulesPath === null) {
+            throw new MissingConfigurationException(
+                'modules_path configuration is required to use module() method'
+            );
+        }
+
+        $prefix = $identifier[0] ?? '';
+
+        foreach ($modulesPath as $basePath) {
+            $modulePath = $basePath . '/' . $prefix . '/' . $routesFile;
+
+            if (file_exists($modulePath)) {
+                $this->loadModuleRoutes($modulePath);
+            }
+        }
+
+        return $this;
+    }
+
+    private function loadModuleRoutes(string $routesFile): void
+    {
+        $moduleRoutes = require $routesFile;
+
+        foreach ($moduleRoutes as $routeData) {
+            if (!isset($routeData['method'], $routeData['path'], $routeData['handler'])) {
+                continue;
+            }
+
+            $this->registerRoute(
+                $routeData['method'],
+                $routeData['path'],
+                $routeData['handler'],
+                $routeData['name'] ?? null
+            );
+        }
+    }
+}
\ No newline at end of file
diff --git a/test_url_generation.php b/test_url_generation.php
new file mode 100644
index 0000000..d9db2c7
--- /dev/null
+++ b/test_url_generation.php
@@ -0,0 +1,11 @@
+#!/usr/bin/env php
+<?php
+
+require __DIR__ . '/vendor/autoload.php';
+
+$router = new Atlas\Router(new Atlas\Config(['modules_path' => ['/tmp']]));
+
+$router->get('/users', 'Handler', 'user_list');
+
+echo "Generated URL: " . $router->url('user_list') . "\n";
+echo "Expected URL: /users\n";
\ No newline at end of file
diff --git a/tests/Unit/RouteMatcherTest.php b/tests/Unit/RouteMatcherTest.php
new file mode 100644
index 0000000..3197870
--- /dev/null
+++ b/tests/Unit/RouteMatcherTest.php
@@ -0,0 +1,140 @@
+<?php
+
+namespace Atlas\Tests\Unit;
+
+use Atlas\Router;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Message\UriInterface;
+
+final class RouteMatcherTest extends TestCase
+{
+    public function testReturnsRouteOnSuccessfulMatch(): void
+    {
+        $config = new \Atlas\Config([
+            'modules_path' => ['/path/to/modules']
+        ]);
+
+        $router = new Router($config);
+
+        $router->get('/hello', 'HelloWorldHandler');
+
+        $uri = $this->createMock(UriInterface::class);
+        $uri->method('getPath')->willReturn('/hello');
+        $uri->method('getScheme')->willReturn('http');
+        $uri->method('getHost')->willReturn('localhost');
+        $uri->method('getPort')->willReturn(80);
+
+        $request = $this->createMock(ServerRequestInterface::class);
+        $request->method('getMethod')->willReturn('GET');
+        $request->method('getUri')->willReturn($uri);
+
+        $matchedRoute = $router->match($request);
+
+        $this->assertInstanceOf(\Atlas\RouteDefinition::class, $matchedRoute);
+        $this->assertSame('/hello', $matchedRoute->getPath());
+        $this->assertSame('HelloWorldHandler', $matchedRoute->getHandler());
+    }
+
+    public function testReturnsNullOnNoMatch(): void
+    {
+        $config = new \Atlas\Config([
+            'modules_path' => ['/path/to/modules']
+        ]);
+
+        $router = new Router($config);
+
+        $router->get('/test', 'Handler');
+
+        $uri = $this->createMock(UriInterface::class);
+        $uri->method('getPath')->willReturn('/other');
+        $uri->method('getScheme')->willReturn('http');
+        $uri->method('getHost')->willReturn('localhost');
+        $uri->method('getPort')->willReturn(80);
+
+        $request = $this->createMock(ServerRequestInterface::class);
+        $request->method('getMethod')->willReturn('GET');
+        $request->method('getUri')->willReturn($uri);
+
+        $matchedRoute = $router->match($request);
+
+        $this->assertNull($matchedRoute);
+    }
+
+    public function testHttpMethodMatchingCaseInsensitive(): void
+    {
+        $config = new \Atlas\Config([
+            'modules_path' => ['/path/to/modules']
+        ]);
+
+        $router = new Router($config);
+
+        $router->get('/test', 'Handler');
+
+        $uri = $this->createMock(UriInterface::class);
+        $uri->method('getPath')->willReturn('/test');
+        $uri->method('getScheme')->willReturn('http');
+        $uri->method('getHost')->willReturn('localhost');
+        $uri->method('getPort')->willReturn(80);
+
+        $request = $this->createMock(ServerRequestInterface::class);
+        $request->method('getMethod')->willReturn('get');
+        $request->method('getUri')->willReturn($uri);
+
+        $matchedRoute = $router->match($request);
+
+        $this->assertNotNull($matchedRoute);
+    }
+
+    public function testRouteCollectionIteratesCorrectly(): void
+    {
+        $config = new \Atlas\Config([
+            'modules_path' => ['/path/to/modules']
+        ]);
+
+        $router = new Router($config);
+
+        $router->get('/route1', 'Handler1');
+        $router->post('/route2', 'Handler2');
+
+        $routes = $router->getRoutes();
+        $this->assertIsIterable($routes);
+
+        $routeArray = iterator_to_array($routes);
+        $this->assertCount(2, $routeArray);
+        $this->assertInstanceOf(\Atlas\RouteDefinition::class, $routeArray[0]);
+        $this->assertInstanceOf(\Atlas\RouteDefinition::class, $routeArray[1]);
+    }
+
+    public function testUrlGenerationWithNamedRoute(): void
+    {
+        $config = new \Atlas\Config([
+            'modules_path' => ['/path/to/modules']
+        ]);
+
+        $router = new Router($config);
+
+        $router->get('/users', 'UserListHandler', 'user_list');
+
+        $url = $router->url('user_list');
+        $this->assertSame('/users', $url);
+    }
+
+    public function testHttpMethodsReturnSameInstanceForChaining(): void
+    {
+        $config = new \Atlas\Config([
+            'modules_path' => ['/path/to/modules']
+        ]);
+
+        $router = new Router($config);
+
+        $methodsResult = $router
+            ->get('/get', 'Handler')
+            ->post('/post', 'Handler')
+            ->put('/put', 'Handler')
+            ->patch('/patch', 'Handler')
+            ->delete('/delete', 'Handler');
+
+        $this->assertTrue($methodsResult instanceof Router);
+    }
+}
\ No newline at end of file
diff --git a/tests/Unit/RouterBasicTest.php b/tests/Unit/RouterBasicTest.php
new file mode 100644
index 0000000..d601db1
--- /dev/null
+++ b/tests/Unit/RouterBasicTest.php
@@ -0,0 +1,89 @@
+<?php
+
+namespace Atlas\Tests\Unit;
+
+use Atlas\Router;
+use PHPUnit\Framework\TestCase;
+
+class RouterBasicTest extends TestCase
+{
+    public function testRouterCanBeCreatedWithValidConfig(): void
+    {
+        $config = new \Atlas\Config([
+            'modules_path' => ['/path/to/modules'],
+            'routes_file' => 'routes.php'
+        ]);
+
+        $router = new Router($config);
+
+        $this->assertInstanceOf(Router::class, $router);
+    }
+
+    public function testRouterCanCreateSimpleRoute(): void
+    {
+        $config = new \Atlas\Config([
+            'modules_path' => ['/path/to/modules']
+        ]);
+
+        $router = new Router($config);
+
+        $router->get('/hello', function() {
+            return 'Hello World';
+        });
+
+        $this->assertCount(1, $router->getRoutes());
+    }
+
+    public function testRouterReturnsSameInstanceForChaining(): void
+    {
+        $config = new \Atlas\Config([
+            'modules_path' => ['/path/to/modules']
+        ]);
+
+        $router = new Router($config);
+
+        $result = $router->get('/get', 'handler')->post('/post', 'handler');
+
+        $this->assertTrue($result instanceof Router);
+    }
+
+    public function testRouteHasCorrectProperties(): void
+    {
+        $config = new \Atlas\Config([
+            'modules_path' => ['/path/to/modules']
+        ]);
+
+        $router = new Router($config);
+
+        $router->get('/test', 'test_handler', 'test_route');
+
+        $routes = $router->getRoutes();
+        $route = $routes[0] ?? null;
+
+        $this->assertInstanceOf(\Atlas\RouteDefinition::class, $route);
+        $this->assertSame('GET', $route->getMethod());
+        $this->assertSame('/test', $route->getPath());
+        $this->assertSame('test_handler', $route->getHandler());
+        $this->assertSame('test_route', $route->getName());
+        $this->assertEmpty($route->getMiddleware());
+        $this->assertEmpty($route->getValidation());
+        $this->assertEmpty($route->getDefaults());
+    }
+
+    public function testRouteNormalizesPath(): void
+    {
+        $config = new \Atlas\Config([
+            'modules_path' => ['/path/to/modules']
+        ]);
+
+        $router = new Router($config);
+
+        $router->get('/api/test', 'handler');
+
+        $routes = $router->getRoutes();
+        $route = $routes[0] ?? null;
+
+        $this->assertInstanceOf(\Atlas\RouteDefinition::class, $route);
+        $this->assertSame('/api/test', $route->getPath());
+    }
+}
\ No newline at end of file