Prague Castle

The Guinness Book of Records calls it the largest ancient castle in the world, and the numbers back that up: nearly 70,000 square meters, 570 meters long, and more than eleven centuries of continuous use as a seat of power. Czech princes, Bohemian kings, Holy Roman Emperors, Nazi Reichsprotektors, and modern presidents have all governed from this hilltop. The castle has changed hands, changed styles, and changed purpose more times than any building in Europe, but it has never stopped being the center of Czech authority.

Prince Borivoj of the Premyslid dynasty founded the castle around 880 AD, and almost every century since has added something. The Romanesque Basilica of St. George dates to 920. The Gothic cathedral took 600 years to finish. The Renaissance gardens were planted by the Habsburgs. The Baroque additions came later. Walk through the complex and you're essentially walking through an architectural history textbook, one courtyard at a time.

The castle's most dramatic chapter might be the Second Defenestration of Prague in 1618, when Protestant nobles threw two Catholic governors and their secretary out of the castle windows. They survived the 21-meter fall — Catholics claimed angels caught them; Protestants said they landed in a dung heap — but the act sparked the Thirty Years' War, which killed eight million people across Europe.

Today the castle is the official residence of the Czech president, and the changing of the guard at noon draws crowds daily. But the real treasure is inside: the Crown Jewels of Bohemia, locked behind a door that requires seven keys held by seven different people to open.