I decided to take an exploratory walk in the neighborhood above the Hauptbahnhof (train station) in Mainz. At one time Mainz was one of the most heavily fortified cities on the Rhine River and there are still sections of the city that have remains of the early citadel and it's outlying fortifications. This one didn't disappoint. In the courtyard behind what once was one of the storage magazines for the citadel, I found this old stone tower and ancient linden tree. Canon T2i, EF S18-55MM at 20mm, ISO 400 on a Manfrotto tripod.