diff --git a/frontend/src/App.css b/frontend/src/App.css
new file mode 100644
index 0000000..8172974
--- /dev/null
+++ b/frontend/src/App.css
@@ -0,0 +1,143 @@
+* {
+  box-sizing: border-box;
+  margin: 0;
+  padding: 0;
+}
+
+:root {
+  --color-bg: #f7f6f2;
+  --color-surface: #ffffff;
+  --color-surface-offset: #f3f0ec;
+  --color-divider: #dcd9d5;
+  --color-text: #28251d;
+  --color-text-muted: #7a7974;
+  --color-primary: #01696f;
+  --color-primary-hover: #0c4e54;
+  --radius-sm: 0.375rem;
+  --radius-md: 0.5rem;
+  --space-2: 0.5rem;
+  --space-3: 0.75rem;
+  --space-4: 1rem;
+  --space-6: 1.5rem;
+  --space-8: 2rem;
+  --font-body: 'Inter', 'Segoe UI', sans-serif;
+}
+
+html, body, #root {
+  height: 100%;
+  font-family: var(--font-body);
+  color: var(--color-text);
+  background: var(--color-bg);
+}
+
+.app {
+  display: grid;
+  grid-template-columns: 220px 1fr;
+  height: 100%;
+}
+
+.sidebar {
+  background: var(--color-surface);
+  border-right: 1px solid var(--color-divider);
+  padding: var(--space-4);
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-2);
+}
+
+.sidebar-title {
+  font-weight: 700;
+  font-size: 1rem;
+  margin-bottom: var(--space-4);
+}
+
+.nav-item {
+  padding: var(--space-2) var(--space-3);
+  border-radius: var(--radius-sm);
+  cursor: pointer;
+  transition: background 0.15s;
+  font-size: 0.9rem;
+}
+
+.nav-item:hover {
+  background: var(--color-surface-offset);
+}
+
+.nav-item.active {
+  background: var(--color-primary);
+  color: #fff;
+}
+
+.main {
+  padding: var(--space-6);
+  overflow: auto;
+}
+
+.header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  margin-bottom: var(--space-6);
+}
+
+.page-title {
+  font-size: 1.25rem;
+  font-weight: 600;
+}
+
+.card {
+  background: var(--color-surface);
+  border: 1px solid var(--color-divider);
+  border-radius: var(--radius-md);
+  padding: var(--space-4);
+}
+
+.table {
+  width: 100%;
+  border-collapse: collapse;
+  font-size: 0.9rem;
+}
+
+.table th, .table td {
+  text-align: left;
+  padding: var(--space-2) var(--space-3);
+  border-bottom: 1px solid var(--color-divider);
+}
+
+.table th {
+  font-weight: 600;
+  color: var(--color-text-muted);
+}
+
+.btn {
+  display: inline-flex;
+  align-items: center;
+  gap: var(--space-2);
+  padding: var(--space-2) var(--space-4);
+  border-radius: var(--radius-sm);
+  border: 1px solid var(--color-divider);
+  background: var(--color-surface);
+  cursor: pointer;
+  font-size: 0.9rem;
+  transition: background 0.15s, border-color 0.15s;
+}
+
+.btn:hover {
+  background: var(--color-surface-offset);
+}
+
+.btn-primary {
+  background: var(--color-primary);
+  color: #fff;
+  border-color: var(--color-primary);
+}
+
+.btn-primary:hover {
+  background: var(--color-primary-hover);
+}
+
+.empty {
+  color: var(--color-text-muted);
+  padding: var(--space-8);
+  text-align: center;
+}
diff --git a/frontend/src/App.tsx b/frontend/src/App.tsx
new file mode 100644
index 0000000..da1a37a
--- /dev/null
+++ b/frontend/src/App.tsx
@@ -0,0 +1,32 @@
+import { useState } from 'react';
+import './App.css';
+import { TopologyView } from './pages/TopologyView';
+import { InventoryView } from './pages/InventoryView';
+import { IPsView } from './pages/IPsView';
+import { DiscoveryJobsView } from './pages/DiscoveryJobsView';
+import type { ViewKey } from './types';
+
+export function App() {
+  const [current, setCurrent] = useState<ViewKey>('inventory');
+
+  const renderView = () => {
+    switch (current) {
+      case 'topology':
+        return <TopologyView />;
+      case 'inventory':
+        return <InventoryView />;
+      case 'ips':
+        return <IPsView />;
+      case 'discovery':
+        return <DiscoveryJobsView />;
+      default:
+        return <InventoryView />;
+    }
+  };
+
+  return (
+    <>
+      {renderView()}
+    </>
+  );
+}
diff --git a/frontend/src/components/AppLayout.tsx b/frontend/src/components/AppLayout.tsx
new file mode 100644
index 0000000..f5ebf20
--- /dev/null
+++ b/frontend/src/components/AppLayout.tsx
@@ -0,0 +1,19 @@
+import { Sidebar } from './Sidebar';
+import type { ViewKey } from '../types';
+
+interface Props {
+  current: ViewKey;
+  onNavigate: (v: ViewKey) => void;
+  children: React.ReactNode;
+}
+
+export function AppLayout({ current, onNavigate, children }: Props) {
+  return (
+    <div className="app">
+      <Sidebar current={current} onChange={onNavigate} />
+      <main className="main">
+        {children}
+      </main>
+    </div>
+  );
+}
diff --git a/frontend/src/components/Sidebar.tsx b/frontend/src/components/Sidebar.tsx
new file mode 100644
index 0000000..1bccee5
--- /dev/null
+++ b/frontend/src/components/Sidebar.tsx
@@ -0,0 +1,30 @@
+import type { ViewKey } from '../types';
+
+interface Props {
+  current: ViewKey;
+  onChange: (v: ViewKey) => void;
+}
+
+const views: { key: ViewKey; label: string }[] = [
+  { key: 'topology', label: 'Topology' },
+  { key: 'inventory', label: 'Inventory' },
+  { key: 'ips', label: 'IPs' },
+  { key: 'discovery', label: 'Discovery Jobs' },
+];
+
+export function Sidebar({ current, onChange }: Props) {
+  return (
+    <aside className="sidebar">
+      <div className="sidebar-title">NetMapper</div>
+      {views.map(v => (
+        <div
+          key={v.key}
+          className={`nav-item ${current === v.key ? 'active' : ''}`}
+          onClick={() => onChange(v.key)}
+        >
+          {v.label}
+        </div>
+      ))}
+    </aside>
+  );
+}
diff --git a/frontend/src/lib/api.ts b/frontend/src/lib/api.ts
new file mode 100644
index 0000000..0ac00b7
--- /dev/null
+++ b/frontend/src/lib/api.ts
@@ -0,0 +1,14 @@
+import type { NetObject } from '../types';
+
+const API_BASE = '/api/v1';
+
+export async function fetchObjects(): Promise<NetObject[]> {
+  // Mock data for now
+  return [
+    { id: '1', name: 'Site HQ', slug: 'site-hq', type: 'site', status: 'active' },
+    { id: '2', name: 'Rack A', slug: 'rack-a', type: 'rack', status: 'active' },
+    { id: '3', name: 'Server Proxmox', slug: 'server-proxmox', type: 'physical_host', vendor: 'Dell', model: 'R730', status: 'active' },
+    { id: '4', name: 'Switch Core', slug: 'switch-core', type: 'switch', vendor: 'Mikrotik', status: 'active' },
+    { id: '5', name: 'Firewall Edge', slug: 'firewall-edge', type: 'firewall', status: 'active' },
+  ];
+}
diff --git a/frontend/src/main.tsx b/frontend/src/main.tsx
index 6cc4900..ee3f745 100644
--- a/frontend/src/main.tsx
+++ b/frontend/src/main.tsx
@@ -1,6 +1,6 @@
 import React from 'react'
 import ReactDOM from 'react-dom/client'
-import { App } from './pages/App'
+import { App } from './App'
 
 ReactDOM.createRoot(document.getElementById('root')!).render(
   <React.StrictMode>
diff --git a/frontend/src/pages/DiscoveryJobsView.tsx b/frontend/src/pages/DiscoveryJobsView.tsx
new file mode 100644
index 0000000..f702a81
--- /dev/null
+++ b/frontend/src/pages/DiscoveryJobsView.tsx
@@ -0,0 +1,14 @@
+import { AppLayout } from '../components/AppLayout';
+
+export function DiscoveryJobsView() {
+  return (
+    <AppLayout current="discovery" onNavigate={() => {}}>
+      <header className="header">
+        <h1 className="page-title">Discovery Jobs</h1>
+      </header>
+      <div className="card">
+        <p className="empty">Job di discovery: prossima implementazione.</p>
+      </div>
+    </AppLayout>
+  );
+}
diff --git a/frontend/src/pages/IPsView.tsx b/frontend/src/pages/IPsView.tsx
new file mode 100644
index 0000000..0fbc985
--- /dev/null
+++ b/frontend/src/pages/IPsView.tsx
@@ -0,0 +1,14 @@
+import { AppLayout } from '../components/AppLayout';
+
+export function IPsView() {
+  return (
+    <AppLayout current="ips" onNavigate={() => {}}>
+      <header className="header">
+        <h1 className="page-title">IPs</h1>
+      </header>
+      <div className="card">
+        <p className="empty">Registro IP: prossima implementazione.</p>
+      </div>
+    </AppLayout>
+  );
+}
diff --git a/frontend/src/pages/InventoryView.tsx b/frontend/src/pages/InventoryView.tsx
new file mode 100644
index 0000000..c6036d7
--- /dev/null
+++ b/frontend/src/pages/InventoryView.tsx
@@ -0,0 +1,48 @@
+import { useState, useEffect } from 'react';
+import { AppLayout } from '../components/AppLayout';
+import { fetchObjects } from '../lib/api';
+
+export function InventoryView() {
+  const [objects, setObjects] = useState<Awaited<ReturnType<typeof fetchObjects>>>([]);
+
+  useEffect(() => {
+    fetchObjects().then(setObjects);
+  }, []);
+
+  return (
+    <AppLayout current="inventory" onNavigate={() => {}}>
+      <header className="header">
+        <h1 className="page-title">Inventory</h1>
+      </header>
+      <div className="card">
+        <table className="table">
+          <thead>
+            <tr>
+              <th>Name</th>
+              <th>Type</th>
+              <th>Vendor</th>
+              <th>Model</th>
+              <th>Status</th>
+            </tr>
+          </thead>
+          <tbody>
+            {objects.length === 0 && (
+              <tr>
+                <td colSpan={5} className="empty">Nessun oggetto</td>
+              </tr>
+            )}
+            {objects.map(o => (
+              <tr key={o.id}>
+                <td>{o.name}</td>
+                <td>{o.type}</td>
+                <td>{o.vendor ?? '-'}</td>
+                <td>{o.model ?? '-'}</td>
+                <td>{o.status ?? '-'}</td>
+              </tr>
+            ))}
+          </tbody>
+        </table>
+      </div>
+    </AppLayout>
+  );
+}
diff --git a/frontend/src/pages/TopologyView.tsx b/frontend/src/pages/TopologyView.tsx
new file mode 100644
index 0000000..7ac0385
--- /dev/null
+++ b/frontend/src/pages/TopologyView.tsx
@@ -0,0 +1,29 @@
+import { useState } from 'react';
+import { AppLayout } from '../components/AppLayout';
+import type { ViewKey } from '../types';
+import { fetchObjects } from '../lib/api';
+
+export function TopologyView() {
+  const [objects, setObjects] = useState<Awaited<ReturnType<typeof fetchObjects>>>([]);
+
+  useState(() => {
+    fetchObjects().then(setObjects);
+  });
+
+  return (
+    <AppLayout current="topology" onNavigate={() => {}}>
+      <header className="header">
+        <h1 className="page-title">Topology</h1>
+      </header>
+      <div className="card">
+        <p className="empty">Vista topologia: prossima implementazione (grafo/annidamento).</p>
+        <div style={{ marginTop: '1rem' }}>
+          <strong>Oggetti mockati:</strong>
+          <pre style={{ marginTop: '0.5rem', fontSize: '0.85rem' }}>
+            {JSON.stringify(objects, null, 2)}
+          </pre>
+        </div>
+      </div>
+    </AppLayout>
+  );
+}
diff --git a/frontend/src/types/index.ts b/frontend/src/types/index.ts
new file mode 100644
index 0000000..efc6ad8
--- /dev/null
+++ b/frontend/src/types/index.ts
@@ -0,0 +1,29 @@
+export type ObjectType = 
+  | 'site'
+  | 'area'
+  | 'rack'
+  | 'physical_host'
+  | 'vm'
+  | 'lxc'
+  | 'app'
+  | 'switch'
+  | 'firewall'
+  | 'router'
+  | 'ap'
+  | 'camera'
+  | 'storage'
+  | 'other';
+
+export interface NetObject {
+  id: string;
+  name: string;
+  slug: string;
+  type: ObjectType;
+  status?: string;
+  vendor?: string;
+  model?: string;
+  serial?: string;
+  notes?: string;
+}
+
+export type ViewKey = 'topology' | 'inventory' | 'ips' | 'discovery';