Frymburk, Castle ruin in Nový Hrádek, Czech Republic.

Frymburk is a castle ruin west of Nový Hrádek above the Olešenka valley in the northwestern Orlické Mountains. Its core is enclosed by a massive wall with rounded corners, and its largest element is a nearly cylindrical bergfried over 18 metres in diameter, partly slumped; the tower gate and wall remnants survive.

The castle was probably built at the start of the 14th century by the lords of Leipa; Matouš of Frymburk is the first documented owner, recorded in 1354. In 1425 Hussite orphans destroyed it for Jan Městecký's support of Sigismund, and Swedish troops burned it in 1638. From the mid-16th century it lay deserted, and after 1800 it was abandoned for good.

The castle gave its name to the Frymburk lordship, which under the Trčka family included Dobruška, Dobřany, Olešnice, Slavoňov and about twenty villages with four farms before being attached to Opočno. Iron ore was mined in the valley below the castle, giving rise to the settlement of Doly.

The ruin stands west of Nový Hrádek above the Olešenka valley in the northwestern Orlické Mountains. It is closed because of the risk of collapse, and part of the tower's facing masonry fell in 2014. A rope playground was set up on the outer bailey shortly before 2020.

The massive round tower, over 18 metres in diameter, was solid: above a small dark chamber lay a larger circular room. In 2014 part of the tower's facing masonry collapsed, and the ruin is closed because of the risk of further falls.