Villa Méditerranée

This guide to Villa Méditerranée on Marseille's waterfront starts with a wildly over-budget showpiece building from 2013, its forty-meter cantilever nearly emptied of visitors within a few years. It then follows diving instructor Henri Cosquer, who in 1985 swam through an underwater cliff crack to find a flooded cave lined with prehistoric paintings of horses, bison and hands. Three divers later died trying to reach the cave themselves, which is why scientists sealed the original passage for good.