Ralsko, Basalt summit in Liberec Region, Czech Republic

Rollberg, called Ralsko in Czech, is an isolated conical hill of 696–698 m in the Česká Lípa district, the highest point of the Bohemian Table. Its summit rock is tephrite, forming a boulder field on the south side, while the flanks are Cretaceous sandstones pierced by volcanic rock; the Gothic Rollburg ruin stands on top.

Ralsko Castle was built in the 13th century and received two residential towers in the 14th century before being abandoned around 1505. The fortress played a central role in controlling the region for centuries before it was eventually left to decay.

The name Rollberg, also recorded as Roll, derives from old Germanic or Celtic roots such as rol, ról, roi or roy, and biblical and Hebrew readings have also been proposed. Cyrillic inscriptions left by Soviet soldiers stationed here after 1968 remain visible on the castle ruin.

A red-marked trail leads from Mimoň past the Vranovské skály and the Juliina vyhlídka to the summit, then descends north to Stráž pod Ralskem. The nearest train stops are Mimoň and Pertoltice pod Ralskem on line 086 from Liberec to Česká Lípa. The eastern flank lay in the Ralsko military training area after 1945; marked routes to the top returned only in 1992.

The 1468 capture was the work of the Six-Cities League (Sechsstädtebund), not a "Bohemian Lusatian League": its troops entered the castle by mingling with cattle returning from pasture. The castle was already recorded as deserted in 1505. Cyrillic inscriptions left by Soviet soldiers stationed here from 1968 are still visible on the ruins.