The Oak behind the Castello del Valentino

Every other tree in Turin that the register dates past two hundred years is a plane. This oak is the exception, and it is the only reason the city's oldest age band contains a second species at all. It stands behind the Castello del Valentino near the rock garden the park calls the Rocaille, four metres round and twenty-eight metres tall. Quercus robur is the oak of northern European woodland and it is near its southern limit here on the Po plain, growing where the water table sits close enough to the surface to carry it through an Italian August. The castle it stands behind was rebuilt in the seventeenth century as the residence of Christine of France, and it has housed the city's engineering and architecture school since 1859, so the oak has spent most of its life being walked past by students who were not looking. The Rocaille is much newer than the tree: the artificial cliffs, streams and grottoes were built in 1961 for Italia 61, the exhibition marking a century of Italian unity. Look for a short heavy trunk and limbs coming off it almost horizontally, which is what an oak does when it grows with space around it.