National Museum of Cambodia
the roof are amazing but don't you know that a lot of bats, Cambodian Freetail species, inhabits them. yes, and a lot of them, in fact National Museum has the largest bat population of any artificial structure in the world (as stated in Lonely planet). Seeing them fly away at sunset may be a spectacular moment but not for the treasures. Luckily, an international organization help raised funds to build a second ceiling to stop the droppings from falling through the collections...hurray, bats are happy, and so the museum patrons.