Under these names are known stone gate and an artificial cave on the way between the castle and the minaret. The names are folk, the cave resembled hell and the stone gate the gate to heaven. Officially, the buildings were called Grotta. The cave is adjacent to the Roman aqueduct, and all three buildings can be found on Grott's Island via the castle pond. The cave, built in the first half of the 19th century by stacking large stones, was supposed to add a bit of mystery and romance to the castle park. It had numerous stained glass windows that let in light and created unusual optical drawings on the walls. The cave is inaccessible to the public.