The Old Senate Chamber S1|01 Room 707 is located on the 7th floor of the administration tower, which is part of Karo5. There are two ways to get to the staircase/elevator of the high-rise building:
Option 1: 1st floor
On the 1st floor of the tower there is a sliding door that leads out to the level of the canteen (by the call-a-bike station).
If you enter the high-rise building through this door, you only have to take the left or right corridor into the stairwell in the middle.