Tenhola Hillfort is an ancient castle on a sandy ridge in Hattula, near Lake Vanajavesi. The hillfort rises 65 meters above the surface of Lake Vanajavesi. About a kilometer northwest is the nearest Iron Age cemetery. Tenhola hillfort is believed to have been in use during the Merovingian and Viking Age (in the 500-1000's) and in the Middle Ages. The findings from hillfort include bones, pieces of pottery, iron slag and fragments of a pearl and neck ring. A rare small medieval cannon or firearm bullet has also been found on the hillfort.
Several remains of rocky walls and buildings have been found on the top of Tenhola hillfort. Reconstruction of a log fence with lookout holes has been built on hillfort. Area on the top is 110 meters long and at its widest 25 meters wide. At the foot of hillfort there is a campfire site. You'll find Tenhola hillfort when you arrive from Parola on Suontaantie or Merventie and turn into the road leading to Tenhola Manor.