Býčí skála (Bull Rock) Cave
The Bull Rock is located in Moravian Karst just north of Brno. It is the longest cave system in the Czech Republic, reaching lengths of up to 13 km. In the past, 450 meters of cave was open but today the cave is closed to the public, reinforced with an iron door.
In 1872, famous archaeologist Jindřich Wankel made a significant discovery here. Clay pots, bronze statues, jewelry made of gold as well as human and animal bones: the remains of more than 40 people were buried here. It was reported that this was a sacrificial place where people and animals were sacrificed during ceremonies.
The people were killed violently, with deep wounds to their skulls and bronze arrowheads piercing their ribs. Some of the human heads were split either lengthwise or crosswise. The people who live in the area experience distressing feelings that make them weak in the knees. There is a lot of negative energy in these areas.
Source : https://prague.tv/en/s72/Directory/c217-Sightseeing-Attractions/n7750-The-Scariest-Places-in-the-Czech-Republic-Part-1