Valletta, Malta

Valletta is the smallest national capital in the European Union, home to roughly 6,000 residents inside its fortified walls. The Knights of Saint John founded the city in 1566, following the Great Siege of 1565, laying out a grid of streets that ranks among the first planned Renaissance cities in Europe. Saint John's Co-Cathedral, completed in 1578, displays Caravaggio's 1608 Beheading of Saint John, the only painting the artist ever signed. The 1571 Grand Master's Palace now accommodates the Maltese Parliament, while the 1731 Manoel Theatre operates as Europe's third-oldest working stage. The UNESCO-listed capital's layered history still leaves questions beneath its limestone streets.