The Felsenburg is a fortified castle and tower in the city of Bern, Switzerland.

It is part of the UNESCO Cultural World Heritage Site of the Old City of Bern and, together with the adjacent Untertorbrücke, it is a cultural property of national significance[1] The Felsenburg was built soon after the construction of the first Untertor Bridge connected the medieval city of Bern to the eastern bank of the Aare river.

It was built as part of the defenses of the city and served to secure the eastern end of the bridge.

During the renovation, the coat of arms of the Bernese city-state were painted on the exterior.

The gate arch was rebuilt and the tower's facade was completely redone.