Some hills here are very valuable, both naturally and culturally. They are called mounds. The west bank of the Mergežeris lake is framed by an elongated hill which is about a half kilometer long. The Kačėniškės mound was once built on this hill. One of its slopes ends on the shore of a lake, the other (western) ends in a swamp. From the top of the mound you can see the lake and Švenčionys heights. There are remnants of former ditches with ramparts on the slopes of the mound.