The Terror House in Budapest is a fantastic museum and an unmissable (if somewhat dark) attraction for anyone who visits the city.
I'm not really sure what the purpose of the original building was, it may have been the police HQ, but it's been perfectly restored as a memorial to the thousands tortured or killed under the communist and fascist regimes (Hungary got it from both ends).
The outside of the building with its eaves spelling the word 'TERROR' onto the sunlit facade is framed in black and stands out against the neighboring, less intimidating buildings. Inside there are lots of video walls constantly bearing witness to the atrocities inflicted on the Hungarian people. Not much is in English but to see the films that's not really important.
Walls are plastered with photos of the era and some walls are even made of prison soap. Once you've walked through the warren of rooms on the upper levels you are shown to what appears to be a normal lift to the lower floors. But once the doors shut the lights go off and the walls come to life as video screens. The lift descends at a snail pace to the basement, all the while showing people recounting their time in the building.
The basement is particularly uncomfortable, especially the single standing room only cells. Not for the claustrophobic.
Overall it was very moving and one of the best curated museums I've seen for a long time.