Falkenstein Castle, Medieval castle ruins in Buchenbach, Germany.

Falkenstein Castle is a ruin standing on a steep rocky crag at 617 meters elevation, marking the entrance to the Höllental valley near Freiburg. The remains consist mainly of wall fragments and foundations scattered across the rocky terrain.

The castle was probably built around 1200 by a Zähringen ministerialis family, the lords of Falkenstein, first recorded between 1137 and 1148. It guarded the Falkensteige route linking the Breisgau with the Baar and Lake Constance. After the Wagensteig valley road built between 1310 and 1379 drew traffic away, the knights allegedly turned to robbery; Freiburg attacked and destroyed the castle on 6 December 1388.

The valley was originally named Falkensteiner Tal after this fortress and its lords, but locals later called it Höllental as time passed. This name shift reflects how the area's identity and local memory changed through the centuries.

Current access to the site is restricted due to structural instability, with only wall fragments and foundations remaining visible from the outside. Visitors should be aware this is a hazardous location and stay clear of any safety barriers or restricted zones.

The castle chapel outlived the fortress: first recorded in 1460 as St. Nicholas' Chapel, it was moved down into the valley by the Höllenbach, today's Rotbach, in 1606. The site also holds a neck ditch about 20 metres long and up to 12 metres deep cut through the ridge.