Holíč Megaliths (also known as Menhirs) are carved stones stored in a lapidary in the courtyard of one of the former manufactory buildings. They come from a prehistoric roundel with a diameter of 60 meters. The structure consisted of 25 stones. The stones were concentrated in 2 circles, alternating low and wide "female" stones with tall and slender "male" stones. In the middle was the main idol. The largest stone is 6.8 meters long (4.5 meters above the ground). The location of cult objects within the roundel and the number and location of stones in them probably had astronomical and especially magical significance.

The stones were discovered in 1988 during excavations under Calvary. In Central Europe, roundels date back to 5,500 to 6,500 years ago. The outer moat of the roundel had a diameter of 60 m, between the moats were 8 stone circular cult structures and 1 structure was in the middle.

The main idol - The Great Stone is decorated with symbols cut to its front and a network of lines, symbols and remnants of paintings on the other sides as well. The most prominent are carved pictures of tools. There are several tools on the Great Stone, the most prominent being a pickaxe, a hammer or an ax in the middle of the stone and a hook or hand-held hoe below it. To the left of the pickaxe is a wheel /a well-known symbol of a deity/. These are the attributes of the Supreme Force that was worshiped in this structure. In the Middle Ages, the Slavs called it Perún or Veles.

The stones are open to the public all year round.