The Palais de l'Île is the small fortified palace sitting on a wedge-shaped islet in the middle of the Thiou canal — built around 1132 and continuously inhabited or in use ever since, which makes it one of the oldest buildings in the city. From the right angle on the canal bridges it looks like a stone ship at anchor, which is why it appears on every postcard of Annecy.
The interior houses a small museum on Annecy's history and on the building's various lives as residence, mint, courthouse and (for most of its career) prison. The cells, the old kitchens, and a fine timbered chapel are all visitable. Modest admission; open daily in summer, closed Tuesdays in winter.