1. Museo Guggenheim, Spain

1. Museo Guggenheim, Spain
Some critics might argue that Frank Gehry'sMuseo Guggenheim in the northern Spanish city of Bilbao, opened in 1997, looks as though it's been taken to by a can-opener, but this is one of the most influential and striking buildings in modern architecture. With its ribbonlike sheets of titanium and its collection of interconnecting blocks, the museum gives a nod to Bilbao's industrialism but also to the saucerlike curves of Frank Lloyd Wright's Solomon R Guggenheim Museum in New York. Oh yeah...nearly forgot. There's art inside, too.