Rundersburg (Hrad)

Austria, Austria

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Rundersburg, also known as Rundersburg Castle, is a ruined medieval castle in the village of Sankt Leonhard am Hornerwald in Lower Austria, located above the Fronbach river valley.

First mentioned in the late 12th century, it was built between about 1180 and 1220 and served as a small hilltop fortress helping to secure a regional trade route together with nearby castles such as Thurnberg and Idolsberg.

The original line of noble owners likely died out in the late 13th century, after which the castle came under the sovereign before gradually falling into ruin; today only fragmentary walls and the base of a once‑central square residential tower remain, and the site is privately owned by the Hoyos family, making it a lesser‑known but historically interesting hill‑ruin in the Waldviertel region.