Medieval walls have been partially preserved in Jena. Its most complete fragment can be seen in the old town gate of St. John. It was one of the gates through which travelers entered the city. It is named in honor of St. John's Church, once stood nearby. The Powder Tower has been preserved near the gate. You can climb on it and enjoy the views of the city from the observation deck. The upper gallery stretches from the tower along the wall, the access to which is also open. The height of the fortress walls in the most part is 12 meters.