Vaduz is the capital of Liechtenstein and the focus of most visits to the country. It is not a large place — the population is around 5,500 — but it has good museums, a pleasant pedestrian zone, and the royal castle looming above it all on a cliff.
The Vaduz Castle is the prince's private residence and cannot be entered, but the walk up from the town is worth doing for the views across the Rhine valley into Switzerland and Austria. The Kunstmuseum (contemporary art), the National Museum (history and culture), and the Postmuseum (stamps and philatelic history) are all within easy walking distance of each other in the town centre. The stamp museum in particular is better than you might expect — it tells the story of how tiny Liechtenstein turned philately into a serious revenue stream.
The pedestrian zone along Städtle has cafés, a few restaurants, and the tourist office where you can get your passport stamped for a fee. The Hofkellerei, the prince's winery just south of the centre, offers tastings of locally produced Pinot Noir and Chardonnay. For more of a walk, the ruined Schalun Castle sits in the forest above town.
Vaduz works well as a half-day or full-day visit from Zurich or Bregenz, but there are hotels if you want to base yourself here and explore the rest of the country on foot or by bike.