The Palais de la Découverte in Paris is one of these lovely spots where science and fun mix. There is a a rumor that the French government might be planning to close it down (sign the petition to save the place).
This is too bad: this may be the only place in the world that has an entire room that is dedicated to a number that is almost, but not quite, entirely unlike π. More specifically, a mathematician named William Shanks spent 20 years of his life computing 707 decimals of π, but only 528 were correct. In 1937, the bogus result was cast in stone in the Palais de la Découverte. The mistake was only discovered in 1945.
In any case, if you think a place like this is worth saving, just click here.