Frýdštejn Castle, Castle ruin in Frýdštejn, Czech Republic

Frýdštejn is a castle ruin standing above the Jizera River valley, built largely by carving directly into and around natural sandstone formations. The fortress features a prominent watch tower and defensive structures that show how medieval builders worked with the natural rock to create fortifications.

Frýdštejn was built in the 14th century, though the exact date is unknown; it is first mentioned in a church source from 1385. In August 1432 Hussites led by Ota of Lozy and Jan Čapek of Sány besieged the castle, whose Catholic lord Bohuš of Kování agreed to a truce and later converted. After a sale in 1556 it lost its watchtower role, and during the Thirty Years' War marauders, deserters and fugitives sheltered in the ruins.

Karolína Světlá set her novel O Krejčíkovic Anežce here, and the ruin later served as a filming location for Tajemství hradu v Karpatech and O princezně Jasněnce a létajícím ševci. Since 1892 the Turnov Adornment Club, which bought it from the Rohan family of Sychrov, has reinforced the surviving masonry; finds from the site are kept in the Turnov Museum.

The ruin lies under a kilometre east of Frýdštejn village centre and its Frýdštejn, náves bus stop. From Malá Skála railway station on line 030 Liberec–Pardubice it is 3 km along the red trail over the Vranovský hřeben ridge. The tower's first-floor entrance is reached by an outdoor metal staircase.

The original entrance's location is unknown; it is thought to have led through the ground floor of the palace to the right of the tower. Today's entrance is a modern addition, reached by an outdoor metal staircase up the tower.