The remains of the Castle can be visited
Birchiburg Castle

The Birchiburg castle ruin, a former hilltop castle, is situated in the rear Möhlintal, below St. Ulrich Monastery on the northern slope of the Birkenberg.
History+
The Birkenberg, where the castle is located, was first documented in 1291 as a “manlehen ze birchiberg”. The castle itself is first mentioned in 1347 in a will as “festi ze Birchiberg”. It belonged to the Schnewlin der Gresser family, who resided here as lords of the castle. Johann Schnewlin der Gresser bequeathed the complex to the sons of his brother Konrad Snewlin von Oberlinden, as his own son was an Augustinian monk. This branch of the family subsequently called themselves “von Birchiberg”. Around 1377/78, the castle met an unknown fate that led to its destruction. It is presumed that it was a punitive action, possibly involving the citizens of Freiburg as part of the Upper Rhenish League of Cities. Between 1998 and 2002, archaeological excavations were carried out on the castle grounds, providing new insights into the complex.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: Andreas Schwarzkopf / CC BY-SA 4.0 via Wikimedia Commons
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 47.9058, 7.8295