The Public Bath House, used as a bath house until 1986. Now it is the Sofia History Museum.
I found the Museum interesting though its focus is on the monarchy and early 1900s, and there really isn't much to see yet.
One of the exhibits explained why Bulgaria, having become "independent" would choose to have a democratically elected monarch. The short answer: everyone else in Europe had a king, so to be treated as a member of the community, Bulgaria needed a king.
Sofia is built atop many mineral springs -- there are taps all around town.
