In the southwestern part of the Karlberg Palace park, there is a mighty, now deceased, oak with a circumference of over 6 metres, called "Karl XII's oak." It is said that Prince Karl, later King Karl XII, used to play here with his siblings, Ulrika Eleonora and Hedvig Sofia, and climbed in the tree's crown. The oak is listed as a natural monument No. 219 in botanist Rutger Sernander's "Stockholm Region's Natural and Cultural Monuments" from 1935.