Whenever a pope is being selected or a current pope grants public audience, St. Peter's Square fills up with eager onlookers. You can usually attend a weekly Papal general audience in St. Peter's Square for free, but you'll have to pick up tickets from the Prefecture of the Papal Household.
At the heart of Vatican City sits St. Peter's Basilica, a baroque-style church where the Holy Father often conducts mass. Located near the spot where St. Peter was thought to have been crucified, the basilica is as much an art museum as a church, with works from the likes of Rafael and Michelangelo on display.
Perhaps the most famous work of art within Vatican City is the Pieta, a marble sculpture by Michelangelo depicting the Virgin Mary holding the body of her son just after he's been removed from the cross. The master of Renaissance art was only 24 when he completed the sculpture.
Another of Michelangelo's famous works, the fresco adorning the ceiling of the Sistine Chapel, took four years to complete at the cost of the artist's eyesight. While Michelangelo considered himself a sculptor, the paintings within the Sistine Chapel are considered to be among his greatest works.
Most visitors don't come to Vatican City to see a staircase, but the set of spiral steps located within the Vatican Museums is one of the most beautiful and most photographed in the world. This particular staircase was the brainchild of Italian designer Guiseppe Momo, built in 1932.
The collection of palaces and lavish apartments that make up the Vatican Museums house one of the world's most extensive and impressive collections of art. Located within the papal palaces, the museums display everything from ancient Egyptian artifacts to Greek sculptures and Italian High Renaissance works.
The expansive St. Peter's Square is impressive even when the Pope isn't holding audience. Seventeenth century architect Lorenzo Bernini designed the area centered around an Egyptian obelisk brought in from the city of Heliopolis on the Nile River delta.
With so much to see within St. Peter's Basilica and the Vatican Museums, most visitors miss the Vatican Gardens entirely. The manicured Italian gardens cover more than half of the Vatican's territory, and have been used by Popes as a quiet respite for hundreds of years.
Sitting next to the Tiber River, Castel Sant'Angelo doesn't immediately seem related to the Vatican. While not originally built for the purpose, Castel Sant'Angelo was converted into a papal fortress complete with a secret passageway to allow the Pope to escape the Vatican in case of danger. You might recognize it from the film Angels and Demons.