Kastelburg, Castle ruin in Waldkirch, Emmendingen, Germany.

Kastelburg is a ruined hilltop castle on a 368.3 m hill about 100 m northwest of Waldkirch's built-up edge. Its 28 m square bergfried, with 12 m sides and walls up to 4 m thick, is climbable as a viewing tower; a rondell and a palas with cellar, ground floor and two upper storeys also survive.

The castle was built in the second half of the 13th century to control trade routes through the valley and secure the authority of its lords. It fell into ruin after destruction in the 1630s.

The castle's name is not explained in the sources, but its role is: with the older Schwarzenburg opposite, it guarded Waldkirch and the trade route through the Elz valley. Since 2002 the Arbeitsgruppe Kastelburg in Not has secured the masonry, and the 28-metre bergfried is climbable as a viewing tower.

The climb is made via marked hiking trails, with several routes starting from Waldkirch and offering different difficulty levels. Good footwear is advisable since the ground is uneven and sometimes slippery.

The 28-metre-high square bergfried, with walls up to 4 metres thick, can be climbed as a viewing tower. The castle also retains a rondell and a palas with cellar, ground floor and two upper storeys. Since 2002 the Arbeitsgruppe Kastelburg in Not has secured the ruin structurally.