Open since May 1, this tightly packed world's fair of architectural hits and misses runs through October 31. UK Pavilion by Tristan Simmonds in collaboration with BDP and Stage One. The first world exposition, held in London in 1851, occupied Joseph Paxton's Crystal Palace. But during the last century, expos (also called world's fairs) evolved into collections of national pavilions that competed for attention with novel and grandiose building designs. The Shanghai Expo in 2010 kicked off the “Asian century” with a show of architectural pyrotechnics that reportedly attracted 73 million visitors. The theme of Expo 2015 in Milan is