The Basilica of Saint Peter's in Rome at the Vatican, is by far the most well known Catholic Church in the world. The altar in the basilica is placed directly above the burial ground of Saint Peter himself, who was crucified and died in Rome in 64 AD. It has since been the tradition to bury Popes under the church, at least the first ones following Peter. Most Papal ceremonies are held at Saint Peter's but the official ecclesiastical seat of the Pope is Saint John Lateran, one of the four main basilicas of Rome.

The origins of Saint Peter's date back to the 4th century when Emperor Constantine I decided to build the basilica to honor the saint's name but the Basilica we see today, built over the original Constantine basilica, was constructed over a hundred year span from1506 to 1626.
The dome was designed by Michelangelo in 1546, who led the project up until the time of his death in 1564, having finished painting the ceiling of the Sistine Chapel some 30 years earlier in 1512.
The dome was vaulted and finished by Giacomo della Porta and Domenico Fontana over 20 year later.
Some years later, in the mid 1600's, Saint Peter's Square began to take shape. The exquisite Baroque style square is lined with an elliptical colonnade, designed by Bernini, which includes two pairs of Doric Pillars and a 13th century Egyptian obelisk.
Two fountains also decorate the square; one done by the artist Carlo Maderno, author of the façade as well, and the other by Bernini who contributed tremendously to the entire masterpiece of both the church and square.
Up until 1990, it was the largest church in the world measuring at 23,000 sq. meters, but was surpassed in size by the Basilica of Our Lady of Peace in Yamoussoukro, on the Ivory Coast in West Africa, which measures 30,000 sq. meters.
Nonetheless, no longer the largest, it is still the most famous and admired Christian church in the world with millions of visitors a year who come to admire the history and beauty of it.