The square in Špania Dolina is dominated by the Knocker, which is currently named after a guesthouse with a restaurant. In its neighborhood, in the half-roofed and repaired building of the original Ferdinand shaft, there is a unique miner's astronomical clock.

Resembling a rock wall, the clockwork opens wide to reveal the magical underground world of the depths of the Špania Dolina copper mine to reveal the miners' toil. The miner's clock shows the work of the miners in the Ferdinand Shaft. The lowering and pulling out of the miners and extracted copper ore was ensured by a two-way wooden water wheel with a diameter of 12 m, which was driven by water supplied by a unique mine water pipe with a length of 32 km. The Ferdinand shaft was created around 1400 and reached a depth of 295 m. The mine corridors connected to it measured 4 km. It was still mined at the beginning of the 20th century.