When was the Vatican built?

The original basilica dates back to the fourth century A.D. New St. Peter's, which replaced the original basilica, dates back to between 1506 and 1615.

In 324, Constantine had the original basilica built to protect the tome of Peter, Christ's disciple. When the basilica was 1,000 years old, between 1309 and 1377, the pope left Rome, and it began to deteriorate. By the early 1500s, the need for a new St. Peter's was obvious. In 1505, Donato Bramante was chosen to design what would become the current Vatican, which was completed between 1506 and 1615 with the help of various other designers, including Michelangelo.