If you are in Berlin, the Stasi museum is worth a visit. It’s in the old Stasi complex.. Be careful not to try to enter the Stasi archive - the people there are not sympathetic to strangers poking their noses in!

It’s full of Stasi spy equipment, memorabilia, other stuff.

They had a whole city block to themselves. Their private hospital is now a regular hospital and as far as I know the only government facilities there now are the archive and the museum.