The Johannistor is the only surviving city gate of medieval Jena, and one of the best-preserved examples of fifteenth-century fortification architecture in Thuringia. It stood at the southern entrance to the old town and is now marooned in the modern city as a pedestrian pass-through, looking slightly surprised to have survived while everything around it was rebuilt.
The tower is built of local limestone and retains much of its original stonework, including the carved decorations above the arch. You can walk through it on the way between the train station and the city centre — it is along the main pedestrian route — and it repays a closer look than most people give it. The view back through the arch toward the university quarter is one of Jena's better urban compositions.