Ocean Expo Park

This guide to Ocean Expo Park in Okinawa asks you to picture something that once floated on the sea beyond the aquarium's glass: Aquapolis, a three-story steel city built for the 1975 Okinawa Ocean Expo by architect Kiyonori Kikutake, a member of Japan's Metabolism movement who believed cities should grow like living things instead of freezing into concrete. Workers welded the settlement together in a Hiroshima shipyard and towed it here, anchored to the seabed rather than the land, complete with its own post office where visitors got a passport stamped mid-ocean. It cost thirteen billion yen and became the symbol of the entire exposition, promising that future neighborhoods might float instead of sprawl.