Valletta, Malta

Valletta, Malta, punches far above its weight as the EU's smallest capital, offering 7,000 years of history within a 0.8-square-kilometer grid you can walk in under 25 minutes. Its 16th-century fortifications are so well-preserved that UNESCO designates the entire city a World Heritage Site. The Mediterranean waters surrounding the peninsula achieve visibility exceeding 30 meters, making them the clearest of any European capital.