The Horse Chestnut of Blokhuispoort

This chestnut spent most of its life outside a prison and now stands outside a library. The Blokhuispoort started as a fifteenth-century citadel, the blokhuis the name comes from, and became the Huis van Bewaring, the city house of detention. Its cell wing went up between 1892 and 1894. The register dates the chestnut to somewhere between 1880 and 1890, so it was in the ground before the masons arrived, and it kept its corner while the cells filled and emptied for the better part of a century. The doors are open now. The complex holds the public library, workspaces and shops, and the walls are one of the few places in Leeuwarden where you can read a book where people once were not allowed to leave. Inspectors found sulphur tuft at the foot of the trunk, a white-rot fungus, at a check around 2017. They rated the tree good anyway and concluded it can safely stay. The ground has been less generous than the inspectors: the register notes that the growing space has increasingly gone over to parked cars, leaving a thin green strip on the canal side. About a hundred and forty years of that, and it still drops conkers every autumn. Only the register has written this one up, so if you know more of its story, tell us.