diff --git a/composer.json b/composer.json
index 53225f0..62a62ba 100644
--- a/composer.json
+++ b/composer.json
@@ -26,7 +26,7 @@
             "@check:migrations",
             "@test"
         ],
-        "test": "vendor/bin/phpunit --bootstrap vendor/autoload.php tests",
+        "test": "vendor/bin/phpunit --bootstrap vendor/autoload.php tests --display-phpunit-notices",
         "start": "php -S localhost:8000 -t public"
     }
 }
diff --git a/src/Controller/NotFoundController.php b/src/Controller/NotFoundController.php
new file mode 100644
index 0000000..2713ebc
--- /dev/null
+++ b/src/Controller/NotFoundController.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace KittyShare\Controller;
+
+use KittyShare\Controller\BaseController;
+use KittyShare\Manager\{ConfigManager, TranslationManager};
+use KittyShare\Translations\Language;
+use KittyShare\Http\{Request, Response, TemplateResponse};
+use Override;
+
+final class NotFoundController extends BaseController
+{
+    #[Override]
+    public function handle(Request $request): Response
+    {
+        return new TemplateResponse(
+            template: "error/404",
+            parameters: [
+                'path' => $request->getUri(),
+                'baseUrl' => ConfigManager::get()->baseUrl,
+                'translationManager' => new TranslationManager(Language::EN), // TODO: Do not hardcode
+            ],
+            statusCode: 404,
+        );
+    }
+}
diff --git a/src/Http/Router.php b/src/Http/Router.php
index 28f3301..517b3cb 100644
--- a/src/Http/Router.php
+++ b/src/Http/Router.php
@@ -2,8 +2,8 @@
 
 namespace KittyShare\Http;
 
+use KittyShare\Controller\NotFoundController;
 use KittyShare\Model\Dependencies;
-use KittyShare\Manager\ConfigManager;
 
 /**
  * The router is responsible for dispatching requests to the correct handler
@@ -90,14 +90,14 @@ public function dispatch(Method $method, string $path): Response
             );
         }
 
-        return new TemplateResponse(
-            template: "error/404",
-            parameters: [
-                'path' => $path,
-                'baseUrl' => ConfigManager::get()->baseUrl,
-            ],
-            statusCode: 404,
-        );
+        return new NotFoundController($this->dependencies)
+            ->handle(
+                new Request(
+                    method: $method,
+                    uri: $path,
+                    parameters: [],
+                )
+            );
     }
 
     /**
diff --git a/src/Manager/TranslationManager.php b/src/Manager/TranslationManager.php
new file mode 100644
index 0000000..1cfc326
--- /dev/null
+++ b/src/Manager/TranslationManager.php
@@ -0,0 +1,44 @@
+<?php
+
+namespace KittyShare\Manager;
+
+use KittyShare\Translations\Language;
+use KittyShare\Translations\TranslationKeys;
+use OutOfBoundsException;
+
+/**
+ * Manages the translation values the application uses
+ */
+final class TranslationManager
+{
+    /**
+     * @var array<string, pure-callable(string...): string|string> The key-value store for the translations
+     */
+    private readonly array $translations;
+
+    public function __construct(Language $language)
+    {
+        /** @var array<string, pure-callable(string...): string|string> $translations */
+        $translations = require __DIR__ . '/../Translations/' . $language->value . '.php';
+
+        $this->translations = $translations;
+    }
+
+    public function get(TranslationKeys $key, string ...$values): string
+    {
+        // If the key does not exist, something went wrong... badly.
+        if (!array_key_exists($key->value, $this->translations)) {
+            throw new OutOfBoundsException(
+                sprintf('Translation key "%s" does not exist.', $key->value),
+            );
+        }
+
+        $translation = $this->translations[$key->value];
+
+        if (is_string($translation)) {
+            return $translation;
+        }
+
+        return $translation(...$values);
+    }
+}
diff --git a/src/Template/error/404.php b/src/Template/error/404.php
index 0c15ada..b7131f5 100644
--- a/src/Template/error/404.php
+++ b/src/Template/error/404.php
@@ -1,18 +1,23 @@
 <?php
-/** @var string $path */
+use KittyShare\Manager\TranslationManager;
+use KittyShare\Translations\TranslationKeys;
+/**
+ * @var string $path
+ * @var TranslationManager $translationManager
+ */
 ?>
 <?php
 require_once __DIR__ . '/../partials/base.php';
 
 $GLOBALS['__kittyshare_base'] = $baseUrl ?? '';
 
-renderHeader("404 Page not found");
+renderHeader($translationManager->get(TranslationKeys::PAGE_404_TITLE));
 ?>
 <main>
-    <h1 class="title">404 Page not found</h1>
-    <p>Hey! It seems like the site that you've tried to access does not exist.</p>
+    <h1 class="title"><?= $translationManager->get(TranslationKeys::PAGE_404_TITLE) ?></h1>
+    <p><?= $translationManager->get(TranslationKeys::PAGE_404_SUBTITLE) ?></p>
 
-    <p class="margin-top-6">Your requested path was &quot;<?= htmlspecialchars($path) ?>&quot;.</p>
+    <p class="margin-top-6"><?= e($translationManager->get(TranslationKeys::PAGE_404_PATHDESC, $path)) ?></p>
 </main>
 <?php
 renderFooter();
diff --git a/src/Translations/Language.php b/src/Translations/Language.php
new file mode 100644
index 0000000..7d179d0
--- /dev/null
+++ b/src/Translations/Language.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace KittyShare\Translations;
+
+enum Language: string
+{
+    case EN = 'en';
+}
diff --git a/src/Translations/TranslationKeys.php b/src/Translations/TranslationKeys.php
new file mode 100644
index 0000000..c63eb5f
--- /dev/null
+++ b/src/Translations/TranslationKeys.php
@@ -0,0 +1,11 @@
+<?php
+
+namespace KittyShare\Translations;
+
+enum TranslationKeys: string
+{
+    case KITTYSHARE_LOGO   = 'kittyshare.logo';
+    case PAGE_404_TITLE    = 'page.404.title';
+    case PAGE_404_SUBTITLE = 'page.404.subtitle';
+    case PAGE_404_PATHDESC = 'page.404.path';
+}
diff --git a/src/Translations/en.php b/src/Translations/en.php
new file mode 100644
index 0000000..f27758f
--- /dev/null
+++ b/src/Translations/en.php
@@ -0,0 +1,10 @@
+<?php
+
+use KittyShare\Translations\TranslationKeys;
+
+return [
+    TranslationKeys::KITTYSHARE_LOGO->value   => 'KittyShare Logo',
+    TranslationKeys::PAGE_404_TITLE->value    => '404 Page not found',
+    TranslationKeys::PAGE_404_SUBTITLE->value => 'Hey! It seems like the site that you\'ve tried to access does not exist.',
+    TranslationKeys::PAGE_404_PATHDESC->value => fn(string $path) => "Your requested path was \"$path\".",
+];
diff --git a/tests/Controller/NotFoundControllerTest.php b/tests/Controller/NotFoundControllerTest.php
new file mode 100644
index 0000000..79a4be1
--- /dev/null
+++ b/tests/Controller/NotFoundControllerTest.php
@@ -0,0 +1,124 @@
+<?php
+
+namespace KittyShare\Tests\Controller;
+
+use KittyShare\Controller\NotFoundController;
+use KittyShare\Http\Request;
+use KittyShare\Http\TemplateResponse;
+use KittyShare\Manager\AuthenticationManager;
+use KittyShare\Manager\ConfigManager;
+use KittyShare\Manager\TranslationManager;
+use KittyShare\Model\Dependencies;
+use KittyShare\Repository\SessionRepository;
+use KittyShare\Repository\SetupRepository;
+use KittyShare\Repository\ShareRepository;
+use KittyShare\Repository\UserRepository;
+use PHPUnit\Framework\TestCase;
+use ReflectionProperty;
+
+final class NotFoundControllerTest extends TestCase
+{
+    private NotFoundController $controller;
+
+    protected function setUp(): void
+    {
+        $userRepository = $this->createStub(UserRepository::class);
+        $sessionRepository = $this->createStub(SessionRepository::class);
+
+        $dependencies = new Dependencies(
+            userRepository: $userRepository,
+            setupRepository: $this->createStub(SetupRepository::class),
+            sessionRepository: $sessionRepository,
+            shareRepository: $this->createStub(ShareRepository::class),
+            authenticationManager: new AuthenticationManager($userRepository, $sessionRepository),
+        );
+
+        $this->controller = new NotFoundController($dependencies);
+    }
+
+    public function testHandleReturnsTemplateResponse(): void
+    {
+        $request = $this->createMock(Request::class);
+        $request->expects(self::once())
+            ->method('getUri')
+            ->willReturn('/missing-page');
+
+        $response = $this->controller->handle($request);
+
+        self::assertInstanceOf(TemplateResponse::class, $response);
+    }
+
+    public function testHandleReturns404StatusCode(): void
+    {
+        $request = $this->createStub(Request::class);
+        $request->method('getUri')->willReturn('/missing-page');
+
+        $response = $this->controller->handle($request);
+
+        self::assertSame(404, $this->getResponseProperty($response, 'statusCode'));
+    }
+
+    public function testHandleUses404Template(): void
+    {
+        $request = $this->createStub(Request::class);
+        $request->method('getUri')->willReturn('/missing-page');
+
+        $response = $this->controller->handle($request);
+
+        self::assertSame('error/404', $this->getResponseProperty($response, 'template'));
+    }
+
+    public function testHandlePassesRequestUriToTemplate(): void
+    {
+        $uri = '/some/nonexistent/page?foo=bar';
+
+        $request = $this->createMock(Request::class);
+        $request->expects(self::once())
+            ->method('getUri')
+            ->willReturn($uri);
+
+        $response = $this->controller->handle($request);
+
+        $parameters = $this->getResponseProperty($response, 'parameters');
+
+        self::assertSame($uri, $parameters['path']);
+    }
+
+    public function testHandlePassesConfiguredBaseUrlToTemplate(): void
+    {
+        $request = $this->createStub(Request::class);
+        $request->method('getUri')->willReturn('/missing-page');
+
+        $response = $this->controller->handle($request);
+
+        $parameters = $this->getResponseProperty($response, 'parameters');
+
+        self::assertSame(ConfigManager::get()->baseUrl, $parameters['baseUrl']);
+    }
+
+    public function testHandlePassesTranslationManagerToTemplate(): void
+    {
+        $request = $this->createStub(Request::class);
+        $request->method('getUri')->willReturn('/missing-page');
+
+        $response = $this->controller->handle($request);
+
+        $parameters = $this->getResponseProperty($response, 'parameters');
+
+        self::assertInstanceOf(
+            TranslationManager::class,
+            $parameters['translationManager'],
+        );
+    }
+
+    /**
+     * Reads a private property from TemplateResponse.
+     */
+    private function getResponseProperty(
+        TemplateResponse $response,
+        string $property,
+    ): mixed {
+        return (new ReflectionProperty(TemplateResponse::class, $property))
+            ->getValue($response);
+    }
+}
diff --git a/tests/Http/TemplateResponseTest.php b/tests/Http/TemplateResponseTest.php
index 05b3c4d..7b2cd88 100644
--- a/tests/Http/TemplateResponseTest.php
+++ b/tests/Http/TemplateResponseTest.php
@@ -2,6 +2,8 @@
 
 use KittyShare\Http\Response;
 use KittyShare\Http\TemplateResponse;
+use KittyShare\Manager\TranslationManager;
+use KittyShare\Translations\Language;
 use PHPUnit\Framework\Attributes\Test;
 use PHPUnit\Framework\TestCase;
 
@@ -51,7 +53,7 @@ public function rendersTemplateWithStatusCode(): void
     {
         $response = new TemplateResponse(
             'error/404',
-            ['path' => '/missing', 'baseUrl' => ''],
+            ['path' => '/missing', 'baseUrl' => '', 'translationManager' => new TranslationManager(Language::EN)],
             404,
         );
 
@@ -72,7 +74,7 @@ public function escapesTemplateParameters(): void
     {
         $response = new TemplateResponse(
             'error/404',
-            ['path' => '/a<b>&"c"', 'baseUrl' => ''],
+            ['path' => '/a<b>&"c"', 'baseUrl' => '', 'translationManager' => new TranslationManager(Language::EN)],
             404,
         );