Valletta, the capital of Malta, is one of the smallest and most concentrated historic areas in the world. Built by the Order of St. John following the Great Siege of 1565, it was the first planned city in Europe, featuring a grid system of streets designed to allow sea breezes to cool the city and to provide a straight line of sight for defense. The city is a masterpiece of Baroque architecture and is almost entirely surrounded by massive limestone bastions and fortifications. UNESCO described it as 'one of the most concentrated historic areas in the world,' with 320 monuments within an area of just 0.55 square kilometers. Valletta is home to St. John's Co-Cathedral, which houses Caravaggio's famous painting, 'The Beheading of Saint John the Baptist.' Despite its small size, it is a bustling administrative center and was the European Capital of Culture in 2018. The city's Grand Harbour is one of the most spectacular natural harbors in the world, having served as a strategic naval base for millennia for the Phoenicians, Romans, and British.