In contrast to the flat roof of the new wing, the old wing’s roof is crowned by three towers. The large round one serves within the museum as a staircase, the other is purely decorative and marks another staircase beneath it. The third tower, now serving with a space for the Clandestine Talks, is square shaped and has now only a functional use in providing access to the roof and functional elements as the lightning rod. Access to it is only possible through a ladder into the attic, then further on a wooden catwalk beneath the roof among wooden beams. Behind a door, a room unfolds holding a further stair leading to the top of the tower. Its dimensions are 3,47 to 3,30 meters which generates an almost squared room. The height of the ceiling is about 2,93 meters and the whole room is not only lit by artificial light but also has a small window of 1,46 to 1,05 meters looking over the building.
Though the space is hidden from inside, the tower itself holds a prominent position on top of the former main entrance of the Wilhelmine era and is visible from all angles outside. With the history of the building as a telegraph office, a post office and now an art museum, the tower overtakes once again the function of a communication hub through the talks and livestream of the Clandestine Talks.