Dagstuhl Castle

Dagstuhl Castle is a ruined castle on the top of a hill near the town of Wadern, kreis Merzig-Wadern, in Saarland, Germany. It overlooks the newer Schloss Dagstuhl in the valley below, which is historic, but has been converted for use as a meeting centre for computer science.

Source: Wikipedia (CC BY-SA 4.0) — https://en.wikipedia.org/wiki/Dagstuhl_Castle