The Stasi Museum is in what was the headquarters of the Ministry of State Security (better known as the Stasi). So you get to see the offices of the head and others. There are photos of the offices in use and they have a good resemblance to the offices now. So they have been preserved well. Perhaps not surprising since the museum is run by volunteers.
You see many objects that you normally associate with James Bond and spying. They have a tree trunk with a built-in camera, a car door with a built-in camera and other gadgets. There was also the map where the line for the Berlin wall was drawn, the map being hidden behind sliding doors.
I bought a book on the history of the Stasi. It is a fascinating history of the organisation. A reasonably good flavour of the Stasi is provided in Deutschland 83 and Deutschland 86 – both enjoyable spy dramas. Some of the episodes are set in the Stasi Museum/HQ.