Hrubá Skála is the largest of the sandstone rock formations in Český ráj, and is located just south of the town of Turnov. It hosts a number of rock castles, most of which were originally constructed in the Medieval period, including Valdštejn and Hrubá Skála castle.

The rocks have been occupied at least since the Neolithic, with numerous archaeological findings, including a site of a Bronze Age forge.

The sandstone plateau was created during the Cretaceous era, when the whole area was a shallow tropical sea in which sand was deposited from the nearby mountain areas. The pure quartz sandstone was exposed when the seas retreated and over the subsequent millions of years has been subject to erosion and tectonic forces, which have created the rock shapes visible today.

Hrubá Skála is an example of a ‘rock city’ in a mature state of evolution, with many individual pillars on the outer edge of the plateau, with more solid blocks in the centre. Today, it is one of the most popular tourist attractions in the region.