This is the largest ancient open-air sanctuary in Lithuania. It is believed to be the site of the Samogitian Duke Vykintas' castle Tvarmenė, near which King Mindaugas was wounded. The historical complex includes a hillfort, a presumed ancient Samogitian sanctuary, mythological stones, and a spring. Sometimes the hillfort is also called Leibiškė or Tverai Hillfort. Pottery artifacts dating back to the 1st millennium AD were found on the western slope of the hillfort. It is also believed that the site may have been a domain of ancient priests,
evidenced by the Lopaičiai stone formations, which could be linked to old religious practices and customs. The main attractions for tourists include:
The Observatory: a small hollow forming a perfect circle with various-sized stones remaining on its slopes.
The Spring: believed to have healing properties.
The Wish Stone: visitors place their own small stone on top of this large stone, hoping their wish will come true.
The Fertility Stone: people sit on this stone and make a wish, hoping to expand their family.