Final answer:
Pope Julius II made the decision to demolish the original Constantinian basilica of St. Peter's Basilica in 1506 and commission the construction of a new basilica. This decision demonstrated his ambitious vision for the papacy and the new basilica became one of the greatest buildings and symbols of the Catholic Church.
Step-by-step explanation:
In 1506, Pope Julius II made the astonishing decision to demolish the original Constantinian basilica of St. Peter's Basilica and commission the construction of a new basilica. The old basilica, erected in the 4th century by Constantine, was in disrepair and needed renovation. Pope Julius II's decision demonstrated his ambitious vision for the papacy and for himself. The new basilica, designed by various architects including Michelangelo, became one of the greatest buildings and symbols of the Catholic Church.