The Tuereiche (Door Oak) of Pfaueninsel

Somebody built a working door into this oak's trunk, and it is still there. The Tuereiche, the Door Oak, stands near the Schloss on Pfaueninsel, its 5.58 metre girth measured just once, in 2017, by a tree registry that has not been back since. Two sources agree on its size and disagree on its species. One calls it a pedunculate oak, the other a sessile oak, working from what looks like the same underlying survey rather than two independent looks at the tree. Berlin's own list of protected trees on the island names four sessile oaks and no pedunculate ones, which tips the balance without settling it outright. Its age, about 250 years by the registry's estimate, is a guess made honestly: nobody has cored it, and the door itself, whatever its original purpose, carries no date of its own. What is certain is the island around it. Pfaueninsel became a royal retreat in 1793, and Friedrich Wilhelm II's gardeners built the new landscape around oaks that already stood there, this one very possibly among them. Reach it by the same short ferry that serves the rest of the island's oaks, then walk toward the Schloss. Look for the door before you look for the tree. Most visitors do it the other way round and miss it entirely.