Edifici de Gas Natural

The work of Enric Miralles, completed in 2005, this shimmering glass waterfront office tower is only 86m (20 storeys) high, but remains extraordinary for its mirrored surface and weirdly protruding adjunct buildings, which could be giant glass cliffs bursting from the main tower’s flank. It's the headquarters for the Naturgy energy company, so visitors can't go inside, but the exterior is still fascinating.