Stelmužė sacred oak is the oldest and thickest growing oak in Lithuania, one of the oldest oaks in Europe. The oak stands in Stelmužė village (Zarasai district). The oak is about 1500 years old, its diameter is 3.5 m, the circumference to the ground is 13 m (8-9 men are needed to cover the trunk).
It was thought that through the Stelmužė sacred oak one could descend into the underworld, that under its roots there might be a treasure, and under its branches, a sacred fire burning since antiquity. At the roots of the tree were burnt altars and offerings to the gods.
Another legend says that some giant decided to overthrow the oak on the carriage of the passing tsar, but one strongman from Stelmužis, who supported that oak, saved the tsar. The arrogant emperor not only did not offer money to this man for salvation but did not even give thanks. Took and smoked his hex. The strongman grabbed the chariot out of resentment, grabbed the wheel, and half of the rim remained in his handful. Maybe that's why half of the rim was depicted on the coat of arms of Stelmužė manor.
It is estimated that the age of Stelmužė oak may reach 1500–2000 m, but there are no more precise conclusions. Biologist B. Alexeyev in the book "Plant Giants and Dwarves" speculates that the legend of Stelmužė may be the oldest oak in all of Europe. The oak was first handled in 1916, then its gravel was clad and it was fenced.
Currently, the condition of Stelmužė oak is bad. The old tree is infested with infections, various species of fungi, algae and moss. Wood cells are stale and difficult to regenerate.