Ralsko Castle, Medieval castle ruin in Svébořice, Czech Republic

Ralsko Castle is a medieval fortress ruin situated on a hilltop with visible stone walls and tower remains. The fragments of stonework allow visitors to understand the basic layout of the former defensive structure, though much has been lost over time.

Written records do not document the castle's exact founding. Archaeology links a stone castle to Jan of Vartenberk in 1377, when the Vartenberks built it in place of an earlier wooden structure to guard trade routes. A garrison held it in 1427, Žitava troops captured it in 1468, and the Bibrštejn family bought the estate in 1505 and let it fall into ruin.

The name Ralsko passed to the Vartenberk family: Jan Chudoba bore the title "of Ralsko" from 1389. Legends recorded at the ruin include a sleeping army in the manner of Blaník, a treasure guarded by a huge dog, and a knight punished by the White Lady.

Access to the castle involves hiking through forest to reach the hilltop location. Sturdy footwear is essential, and visitors should plan adequate time for the climb and exploration of the site.

The hilltop and castle lie within the Ralsko nature reserve, and the site was closed to the public from 1969 to 1990 as part of a Soviet military area; the lookout tower burned down during that period. The castle itself is not recorded as a building in the land register, only as part of the plot.