Vatican City

For most of its history the pope was not only a priest but a king, ruling a broad band of central Italy called the Papal States. That ended in 1870, when the newly united Kingdom of Italy seized Rome for its capital. The furious pope shut himself behind the Vatican walls and refused to step outside; for nearly sixty years popes called themselves "prisoners in the Vatican." The deadlock broke only in 1929, when Pope Pius XI and Italy's dictator Benito Mussolini signed the Lateran Treaty. With a few strokes of a pen it created the country you visit today — the smallest sovereign state on earth, with its own stamps and a pope who is at once spiritual leader and head of state.

Guarding him is one of the strangest armies in the world. The Swiss Guard, founded in 1506, still wears striped blue-and-gold uniforms and carries long pikes — but the pageantry hides real blood. In 1527, when mutinous imperial troops sacked Rome, 147 guardsmen died holding the attackers off so the pope could escape. New recruits still swear their oath each May 6, the anniversary of that stand. And when a pope dies, the whole world watches a chimney: cardinals lock themselves in the Sistine Chapel to choose a successor, and black smoke means no decision while white smoke means they have a pope.

Most visitors first meet Bernini's vast oval piazza, ringed by 284 columns the sculptor shaped into two arms reaching out to embrace the crowd, with an Egyptian obelisk at its center hauled to Rome nearly two thousand years ago. Inside the basilica the hush is immense, and you lose all sense of size until you spot people like ants beneath the dome. To one side, behind bulletproof glass, sits Michelangelo's Pietà — Mary cradling her dead son — carved when he was barely in his mid-twenties. The lines are long and the crowds thick, yet step across the line marked in the pavement and you have quietly left Italy for another country.