If memories of math class give you nightmares, this museum may not be for you. If they don't, you may well find this expansive collection of mechanical calculating machines – from the abacus to early computers by Hollerith and Babbage – quite fascinating. The science aspect is complemented by changing art exhibits, usually with a geometric constructivist bent. Work your way down from the top floor of the large minimalist glass-and-steel cube.
Arithmeum
Bonn