Fort Canning Park Tree Tunnel, Singapore

Things are looking up for Singapore. Powered by one of the world's most important ports, the nation often places near the top in rankings of economic and human development. Singaporeans have managed to balance their high population density—second among nation states only to Monaco—with their region's natural beauty. This tree-canopied spiral staircase is part of a pedestrian 'Tree Tunnel' through Fort Canning Park, one of many carefully planned green spaces within the bustling city-state.