The Ekeby oak is approximately 500 years old.[2] It was declared a natural monument in 1956.[3] There are many old trees around Ekebyhov Castle; the oak, sometimes called Ekeröjätten (the Ekerö giant) stands alone in a field south of the castle, where it had no competition for space from other trees.[4] It was measured in 2008 as the largest tree by volume in Sweden.[5]