diff --git a/frontend/package-lock.json b/frontend/package-lock.json
index ccca8ea..f385a44 100644
--- a/frontend/package-lock.json
+++ b/frontend/package-lock.json
@@ -11,7 +11,8 @@
         "@tanstack/react-query": "^5.74.4",
         "@tanstack/react-query-devtools": "^5.74.6",
         "react": "^19.0.0",
-        "react-dom": "^19.0.0"
+        "react-dom": "^19.0.0",
+        "react-router-dom": "^7.5.1"
       },
       "devDependencies": {
         "@eslint/js": "^9.22.0",
@@ -1934,6 +1935,15 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/cookie": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/cookie/-/cookie-1.0.2.tgz",
+      "integrity": "sha512-9Kr/j4O16ISv8zBBhJoi4bXOYNTkFLOqSL3UDB0njXxCXNezjeyVrJyGOWtgfs/q2km1gwBcfH8q1yEGoMYunA==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=18"
+      }
+    },
     "node_modules/cross-spawn": {
       "version": "7.0.6",
       "resolved": "https://registry.npmjs.org/cross-spawn/-/cross-spawn-7.0.6.tgz",
@@ -2905,6 +2915,45 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/react-router": {
+      "version": "7.5.1",
+      "resolved": "https://registry.npmjs.org/react-router/-/react-router-7.5.1.tgz",
+      "integrity": "sha512-/jjU3fcYNd2bwz9Q0xt5TwyiyoO8XjSEFXJY4O/lMAlkGTHWuHRAbR9Etik+lSDqMC7A7mz3UlXzgYT6Vl58sA==",
+      "license": "MIT",
+      "dependencies": {
+        "cookie": "^1.0.1",
+        "set-cookie-parser": "^2.6.0",
+        "turbo-stream": "2.4.0"
+      },
+      "engines": {
+        "node": ">=20.0.0"
+      },
+      "peerDependencies": {
+        "react": ">=18",
+        "react-dom": ">=18"
+      },
+      "peerDependenciesMeta": {
+        "react-dom": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/react-router-dom": {
+      "version": "7.5.1",
+      "resolved": "https://registry.npmjs.org/react-router-dom/-/react-router-dom-7.5.1.tgz",
+      "integrity": "sha512-5DPSPc7ENrt2tlKPq0FtpG80ZbqA9aIKEyqX6hSNJDlol/tr6iqCK4crqdsusmOSSotq6zDsn0y3urX9TuTNmA==",
+      "license": "MIT",
+      "dependencies": {
+        "react-router": "7.5.1"
+      },
+      "engines": {
+        "node": ">=20.0.0"
+      },
+      "peerDependencies": {
+        "react": ">=18",
+        "react-dom": ">=18"
+      }
+    },
     "node_modules/resolve-from": {
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/resolve-from/-/resolve-from-4.0.0.tgz",
@@ -3006,6 +3055,12 @@
         "semver": "bin/semver.js"
       }
     },
+    "node_modules/set-cookie-parser": {
+      "version": "2.7.1",
+      "resolved": "https://registry.npmjs.org/set-cookie-parser/-/set-cookie-parser-2.7.1.tgz",
+      "integrity": "sha512-IOc8uWeOZgnb3ptbCURJWNjWUPcO3ZnTTdzsurqERrP6nPyv+paC55vJM0LpOlT2ne+Ix+9+CRG1MNLlyZ4GjQ==",
+      "license": "MIT"
+    },
     "node_modules/shebang-command": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/shebang-command/-/shebang-command-2.0.0.tgz",
@@ -3136,6 +3191,12 @@
         "typescript": ">=4.8.4"
       }
     },
+    "node_modules/turbo-stream": {
+      "version": "2.4.0",
+      "resolved": "https://registry.npmjs.org/turbo-stream/-/turbo-stream-2.4.0.tgz",
+      "integrity": "sha512-FHncC10WpBd2eOmGwpmQsWLDoK4cqsA/UT/GqNoaKOQnT8uzhtCbg3EoUDMvqpOSAI0S26mr0rkjzbOO6S3v1g==",
+      "license": "ISC"
+    },
     "node_modules/type-check": {
       "version": "0.4.0",
       "resolved": "https://registry.npmjs.org/type-check/-/type-check-0.4.0.tgz",
diff --git a/frontend/package.json b/frontend/package.json
index 6f69164..311d9d7 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -13,7 +13,8 @@
     "@tanstack/react-query": "^5.74.4",
     "@tanstack/react-query-devtools": "^5.74.6",
     "react": "^19.0.0",
-    "react-dom": "^19.0.0"
+    "react-dom": "^19.0.0",
+    "react-router-dom": "^7.5.1"
   },
   "devDependencies": {
     "@eslint/js": "^9.22.0",
diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
index 9af05cd..42fc738 100644
--- a/frontend/src/App.tsx
+++ b/frontend/src/App.tsx
@@ -2,16 +2,20 @@ import { useState } from "react";
 import Panel from "./components/Panel";
 
 import { useQueries } from "@tanstack/react-query";
+import { useNavigate } from "react-router-dom";
 import "./App.css";
 import ArticleSelector from "./components/ArticleSelector";
-import CelexSelector from "./components/CelexSelector";
 import TOC from "./components/TOC";
 import { getArticleIds, getToc } from "./lib/api";
 import { Language } from "./lib/types";
 
-function App() {
-  const [celexId, setCelexId] = useState("32024R1689");
-  const [selectedArticle, setSelectedArticle] = useState<number>(1);
+type Props = {
+  celexId: string;
+  articleId: number;
+};
+
+function App({ celexId, articleId }: Props) {
+  const navigate = useNavigate();
   const [numPanels, setNumPanels] = useState(1);
   const [selectedParagraphId, setSelectedParagraphId] = useState<string | null>(
     null
@@ -35,10 +39,10 @@ function App() {
   const error = results.find((result) => result.isError);
 
   if (isPending) {
-    return <div>Loading...</div>;
+    return <div className="panel">Loading...</div>;
   }
   if (error) {
-    return <div>Error: {error.error?.message}</div>;
+    return <div className="panel">Error: {error.error?.message}</div>;
   }
 
   const examples = [
@@ -56,9 +60,7 @@ function App() {
             id="examples"
             value={celexId}
             onChange={(e) => {
-              setSelectedArticle(1);
-              setSelectedParagraphId(null);
-              setCelexId(e.currentTarget.value);
+              navigate(`/${e.target.value}`);
             }}
           >
             {examples.map((example) => (
@@ -68,11 +70,11 @@ function App() {
             ))}
           </select>
         </div>
-        <CelexSelector defaultId={celexId} onSelected={setCelexId} />
+        {/* <CelexSelector defaultId={celexId} onSelected={setCelexId} /> */}
         <ArticleSelector
           articleIds={results[0].data!}
-          selectedId={selectedArticle}
-          onSelected={setSelectedArticle}
+          selectedId={articleId}
+          onSelected={(id) => navigate(`/${celexId}/articles/${id}`)}
         />
         <button onClick={() => setNumPanels((prev) => prev + 1)}>
           Add Panel
@@ -81,8 +83,8 @@ function App() {
       <div className="panel-container">
         <TOC
           toc={results[1].data!}
-          selectedArticleId={selectedArticle}
-          onArticleSelected={setSelectedArticle}
+          selectedArticleId={articleId}
+          onArticleSelected={(id) => navigate(`/${celexId}/articles/${id}`)}
         />
         {Array.from({ length: numPanels }, (_, index) => (
           <Panel
@@ -91,7 +93,7 @@ function App() {
             language={
               Object.values(Language)[index % Object.values(Language).length]
             }
-            articleId={selectedArticle}
+            articleId={articleId}
             selectedParagraphId={selectedParagraphId || undefined}
             onParagraphSelected={setSelectedParagraphId}
           />
diff --git a/frontend/src/MainView.tsx b/frontend/src/MainView.tsx
new file mode 100644
index 0000000..9f84420
--- /dev/null
+++ b/frontend/src/MainView.tsx
@@ -0,0 +1,13 @@
+import { useParams } from "react-router-dom";
+import App from "./App";
+
+function MainView() {
+  const { celexId, articleId } = useParams();
+  if (!celexId) {
+    return <div>Error: No CELEX ID provided</div>;
+  }
+  return (
+    <App celexId={celexId} articleId={articleId ? parseInt(articleId) : 1} />
+  );
+}
+export default MainView;
diff --git a/frontend/src/components/LanguageSwitcher.tsx b/frontend/src/components/LanguageSwitcher.tsx
index 10dfea3..25d7e3b 100644
--- a/frontend/src/components/LanguageSwitcher.tsx
+++ b/frontend/src/components/LanguageSwitcher.tsx
@@ -1,5 +1,4 @@
 import { Language } from "../lib/types";
-
 import "./LanguageSwitcher.css";
 
 function LanguageSwitcher({
diff --git a/frontend/src/components/MainApp.tsx b/frontend/src/components/MainApp.tsx
new file mode 100644
index 0000000..e69de29
diff --git a/frontend/src/components/TOC.css b/frontend/src/components/TOC.css
index 9411452..f927f11 100644
--- a/frontend/src/components/TOC.css
+++ b/frontend/src/components/TOC.css
@@ -8,22 +8,23 @@
     min-width: 0;
   }
 
-  transition: width 0.3s ease-in-out;
-
   overflow: scroll;
   max-height: 100vh;
 
-  .division-list {
-    list-style: none;
+  .toc-division {
+    margin-block: 0.5rem;
+    cursor: pointer;
+  }
 
-    ul {
-      margin-block: 1rem;
-    }
+  ul {
+    padding: 1rem;
+    list-style-type: disc;
   }
 
   .selected {
     font-weight: bold;
   }
+
   .article {
     cursor: pointer;
   }
diff --git a/frontend/src/components/TOC.tsx b/frontend/src/components/TOC.tsx
index 2aae217..c16e3e4 100644
--- a/frontend/src/components/TOC.tsx
+++ b/frontend/src/components/TOC.tsx
@@ -1,19 +1,7 @@
 import { useState } from "react";
+import { Division } from "../lib/types";
 import "./TOC.css";
 
-type Article = {
-  type: "article";
-  id: number;
-  title: string;
-  subtitle: string;
-};
-type Division = {
-  type: "division";
-  title: string;
-  subtitle: string;
-  articles: Article[];
-};
-
 type TOC = Division[];
 
 type TOCProps = {
@@ -23,6 +11,49 @@ type TOCProps = {
 };
 
 function TOC({ toc, selectedArticleId, onArticleSelected }: TOCProps) {
+  function containsArticle(division: Division, articleId: number): boolean {
+    return division.content.some((c) => {
+      if (c.type === "division") {
+        return containsArticle(c, articleId);
+      }
+      return c.type === "article" && c.id === articleId;
+    });
+  }
+  function renderDivision(division: Division) {
+    return (
+      <details
+        key={division.title}
+        className={`toc-division level-${division.level}`}
+        open={
+          !!selectedArticleId && containsArticle(division, selectedArticleId)
+        }
+      >
+        <summary>
+          {division.title}: {division.subtitle}
+        </summary>
+        <ul>
+          {division.content.map((c) => {
+            if (c.type === "division") {
+              return renderDivision(c);
+            } else {
+              return (
+                <li
+                  key={c.id}
+                  className={[
+                    "article",
+                    selectedArticleId === c.id ? "selected" : "",
+                  ].join(" ")}
+                  onClick={() => onArticleSelected(c.id)}
+                >
+                  {c.title}: {c.subtitle}
+                </li>
+              );
+            }
+          })}
+        </ul>
+      </details>
+    );
+  }
   const [isVisible, setIsVisible] = useState(true);
 
   return (
@@ -33,29 +64,7 @@ function TOC({ toc, selectedArticleId, onArticleSelected }: TOCProps) {
       >
         {isVisible ? "<" : ">"}
       </button>
-      <ul className="division-list">
-        {toc.map((division, index) => (
-          <li key={index}>
-            <strong>{division.title}</strong>
-            <br />
-            {division.subtitle}
-            <ul>
-              {division.articles.map((article) => (
-                <li
-                  key={article.id}
-                  className={[
-                    "article",
-                    selectedArticleId === article.id ? "selected" : "",
-                  ].join(" ")}
-                  onClick={() => onArticleSelected(article.id)}
-                >
-                  {article.title}: <em>{article.subtitle}</em>
-                </li>
-              ))}
-            </ul>
-          </li>
-        ))}
-      </ul>
+      {toc.map((division) => renderDivision(division))}
     </nav>
   );
 }
diff --git a/frontend/src/lib/types.ts b/frontend/src/lib/types.ts
index 74ed8df..04f08f8 100644
--- a/frontend/src/lib/types.ts
+++ b/frontend/src/lib/types.ts
@@ -5,5 +5,19 @@ enum Language {
   ITA = "ita",
   ESP = "esp",
 }
+type Article = {
+  type: "article";
+  id: number;
+  title: string;
+  subtitle: string;
+};
+type Division = {
+  type: "division";
+  title: string;
+  subtitle: string;
+  level: number;
+  content: Article[] | Division[];
+};
 
 export { Language };
+export type { Article, Division };
diff --git a/frontend/src/main.tsx b/frontend/src/main.tsx
index c6be869..6753157 100644
--- a/frontend/src/main.tsx
+++ b/frontend/src/main.tsx
@@ -2,7 +2,9 @@ import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
 import { ReactQueryDevtools } from "@tanstack/react-query-devtools";
 import { StrictMode } from "react";
 import { createRoot } from "react-dom/client";
-import App from "./App.tsx";
+import { BrowserRouter, Route, Routes } from "react-router-dom";
+import MainView from "./MainView";
+
 import "./index.css";
 
 const queryClient = new QueryClient();
@@ -11,7 +13,14 @@ createRoot(document.getElementById("root")!).render(
   <StrictMode>
     <QueryClientProvider client={queryClient}>
       <ReactQueryDevtools />
-      <App />
+      <BrowserRouter>
+        <Routes>
+          <Route index element={<div>Select a CELEX ID</div>} />
+          <Route path=":celexId/articles?/:articleId?">
+            <Route index element={<MainView />} />
+          </Route>
+        </Routes>
+      </BrowserRouter>
     </QueryClientProvider>
   </StrictMode>
 );
diff --git a/src/formex_viewer/server.py b/src/formex_viewer/server.py
index 8b45c0f..1567aa9 100644
--- a/src/formex_viewer/server.py
+++ b/src/formex_viewer/server.py
@@ -28,7 +28,7 @@ type CacheKey = tuple[str, Language]
 CACHE: dict[CacheKey, str] = {}
 
 
-def _get_fmx4_data(celex_id: str, language: Language) -> str:
+def _get_fmx4_data(celex_id: str, language: Language) -> ET.Element:
     """
     Fetch the FMX4 data from the server.
     """
@@ -43,9 +43,10 @@ def _get_fmx4_data(celex_id: str, language: Language) -> str:
     )
     fmx4_data = client.publication_text(cellar_id, ContentType.ZIP_FMX4)
 
-    CACHE[(celex_id, language)] = fmx4_data
+    xml = ET.fromstring(fmx4_data.encode("utf-8"))
+    CACHE[(celex_id, language)] = xml
 
-    return fmx4_data
+    return xml
 
 
 @app.get("/{celex_id}/articles")
@@ -53,8 +54,7 @@ def article_ids(celex_id: str, language: Language = Language.ENG):
     """
     Fetch the article IDs from the server.
     """
-    fmx4_data = _get_fmx4_data(celex_id, language)
-    xml = ET.fromstring(fmx4_data.encode("utf-8"))
+    xml = _get_fmx4_data(celex_id, language)
 
     article_xpath = "//ARTICLE/@IDENTIFIER"
     article_ids = xml.xpath(article_xpath)
@@ -65,18 +65,16 @@ def article_ids(celex_id: str, language: Language = Language.ENG):
 
 @app.get("/{celex_id}/toc/{language}")
 def toc(celex_id: str, language: Language = Language.ENG):
-    """
-    Fetch the table of contents from the server.
-    """
-    fmx4_data = _get_fmx4_data(celex_id, language)
-    xml = ET.fromstring(fmx4_data.encode("utf-8"))
-
-    toc = []
-
-    for division in xml.xpath("//DIVISION"):
+    def _handle_division(division: ET.Element, level: int):
         print(division)
+
         title = ti_el[0] if (ti_el := division.xpath("TITLE/TI//text()")) else ""
         subtitle = sti_el[0] if (sti_el := division.xpath("TITLE/STI//text()")) else ""
+
+        subdivisions = []
+        for subdivision in division.xpath("DIVISION") or []:
+            subdivisions.append(_handle_division(subdivision, level + 1))
+
         articles = []
         for article in division.xpath("ARTICLE") or []:
             art_id = article.get("IDENTIFIER")
@@ -94,14 +92,23 @@ def toc(celex_id: str, language: Language = Language.ENG):
                     "subtitle": art_subtitle,
                 }
             )
-        toc.append(
-            {
-                "title": title,
-                "type": "division",
-                "subtitle": subtitle,
-                "articles": articles,
-            }
-        )
+
+        return {
+            "type": "division",
+            "title": title,
+            "subtitle": subtitle,
+            "level": level,
+            "content": subdivisions + articles,
+        }
+
+    """
+    Fetch the table of contents from the server.
+    """
+    xml = _get_fmx4_data(celex_id, language)
+    toc = []
+
+    for division in xml.xpath("//ENACTING.TERMS/DIVISION"):
+        toc.append(_handle_division(division, 0))
 
     return toc
 
@@ -111,8 +118,7 @@ def article(celex_id: str, article_id: int, language: Language = Language.ENG):
     """
     Fetch an article from the server.
     """
-    fmx4_data = _get_fmx4_data(celex_id, language)
-    xml = ET.fromstring(fmx4_data.encode("utf-8"))
+    xml = _get_fmx4_data(celex_id, language)
 
     article_xpath = "//ARTICLE"
     articles = xml.xpath(article_xpath)