The ruins of the Pajrek castle lie above the town Nýrsko in the western part of the Šumava mountains (Bohemian Forest), 505 m a.s.l.

This important borderline castle was established at the beginning of the 14th century. In 1472 it was already abandoned. In 1504 the castle was reconstructed, but it was only used till the middle of the 16th century, when it was finally abandoned.

Only the remains of the huge tower have been preserved up till the present day. Traces of the small tower can be seen too. It was connected with the main tower by a drawbridge. The remains of the walls, the gate and the moats can be found around here.

The ruins lie on the green marked trail about 1.5 km far from Nýrsko.