Cisternerne Museum of Modern Glass Art, Copenhagen, Denmark

Located under Copenhagen's old water supply tanks, the walls of this eerie cavern seep water onto the stone floor, reflecting the dramatically lit sculpture gallery. Gallery director and sculptor Max Seidenfaden considers it a water-feature. The moist air and a constant temperature of around 46-50 degrees means that only durable works made from glass, stone or metal can be exhibited. "There are no windows so we control the light and the overall atmosphere. When the water, light and quietness come together, it really is magical," says Seidenfaden.