Čertová ruka is an ancient fortified site located in centre of the Hrubá Skála rocks. It is one of the best protected of any site in the region, with cliffs on three sides and only a very steep and narrow access path. Archaeological finds dating from the Neolithic, Bronze and Iron Ages have been found at the site, and it was also used in the Medieval period. There is evidence that the site was used in the late Bronze Age by the ‘Urnfield’ people as a manufacturing site for Bronze goods.

The site is difficult to access, with only a faint trail leading up to the rocks from the eastern side, and some scrambling needed to reach the summit rocks.

See link for more information (in Czech)