Vildštejn, Castle ruin in Seč, Czech Republic.

Vildštejn is a castle ruin on a rocky spur above the Chrudimka valley, one kilometre south of Seč. Its tower palace had an irregular plan, with a storeroom and household rooms on the ground floor and the owner's dwelling above; a second building stood to the south, and walls ran along the slope edge. Remains of a bastion and a tower with a Gothic window survive.

The fortress was constructed in the late 13th century and initially belonged to Hrabiš von Poběnice. It was later besieged multiple times, particularly during the Hussite Wars, which shows its strategic importance in the region.

The ruin has been protected as a cultural monument of the Czech Republic. Its name appears in several forms, including Vilštejn, Vilštán, Vichštejn and the German Wildenstein. A surviving tower fragment with a Gothic window is the detail to look for.

The ruin can be reached via a marked hiking trail from Seč that passes through a 30 meter tunnel built during the reservoir's construction. The trail is well-marked and offers an interesting mix of walking and historical surroundings.

The road on the dam crest runs through a 30-metre tunnel blasted beneath the ruin between 1924 and 1934, when the Seč Reservoir was built. The castle's remaining tower fragments were demolished during that construction.