Furthermore, the optical intruments are very sensitive against dust and humidity due to the open construction of the telescope inside the building. However, you can visit a part of the inside of the building, i.e. the ground floor and the main room only during guided tours. Pre-registration is necessary because the number of participants is restricted. It shows the history of the area and the Einsteinturm in great detail. To have a look at the impressive refractor , now also newly renovated, is also worth a visit.
Entrance is free.