Stelmužė oak is Lithuania natural monument, one of the oldest oak trees in Europe and the oldest tree in Lithuania. It is believed that the age of the oak is 1000 - 1500 or even 2000 years. Oak is 23 m in height, 3.5 m in diameter and 13 m in girth on the ground level (8-9 men are needed to fully embrace the trunk).

Stelmužė oak - is a tree which has seen a lot during his life. Lithuanian dukes, crusaders, Knights of the Sword, Swedish armies have been here. Kaiser and Hitler armies passed by this place. A human skeleton and a French rifle found in the hollow suggests that it probably was a hiding place of one of the Napoleonic soldiers, when he was on his way from Russia.