Festungsruine Hohentwiel

Singen, Germany, Germany

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Festungsruine Hohentwiel is a large medieval fortress ruin perched on the flat, 868‑meter‑high peak of the extinct Hohentwiel volcano just outside the town of Singen am Hohentwiel in Baden‑Württemberg, Germany.

Covering about nine hectares, it is one of the biggest and most visited castle ruins in the country, first built in the 10th century as a residence for the Dukes of Swabia and later expanded into a major Württemberg state fortress and even a prison.

Today the site preserves extensive walls, bastions, tunnels, and scattered ruins that give a clear sense of the former fortress, and visitors can hike up from Singen to enjoy sweeping views across the Lake Constance region and the Alps, with an information center and seasonal guided tours helping to explain the long and layered history of the mountain stronghold.