VATICAN CORNER

Saint Peter’s Basilica is the largest church in the world at 163,180 sq. ft., and with a maximum capacity of 60,000 people. During the years 319 to 349 AD, the first Christian Emperor of Rome – Constantine built the first Saint Peter’s Basilica over the small shrine marking the burial place of Saint Peter. Eventually the Basilica was not large enough and in the middle of the fifteenth century it began to collapse from age. Pope Julius II and architect Donato Bramante made plans to completely rebuild the Basilica. Following the examples set by emperors and sultans, the Pope decided to crown the Basilica with a dome. The construction lasted for 120 years, beginning in 1506 with 2,500 construction workers starting with four years of rapid construction. However after that, there were times of very slow progress due to lack of funds, poor leadership or both. The project was controlled by successive popes and their architects, resulting in different design decisions that made the construction progress inefficiently. During the construction only those parts of the old Basilica that immediately interfered with the new construction were torn down. It was unclear which parts of the old Basilica were to be incorporated into the new Basilica. The construction started in an unusual manner, building from the inside out, and in doing so this allowed experimenting with the final shape. The design of the dome along with the floor layout changed multiple times. The final decision made by architect Carl Maderno, who finished the Basilica, was to have a building in the shape of a Latin cross with one arm that is longer than the other three, as opposed to a Greek cross with all the arms of equal length. That decision created more internal space but made the dome only visible from a distance. The first architect Bramante used working plans as well as scale models in wood and clay to communicate his designs to the masons and stonecutters. When the famous Raphael became head architect in 1514 he created drawings with 3 views, plan, profile and section, so the workmen had more details and it freed Raphael from being at the construction site all the time. The foundation trench for each of the massive 90 foot high piers was constructed 25 feet deep, requiring baskets with a series of pulleys to raise the dirt. Soaring above the piers at 150 feet were to be the dome and the barrel vaults, but no one had ever spanned such a large distance at such a large height before and there were serious concerns about the foundation and whether it could hold the enormous weight. Not long after the first architect Bramante died, cracks began to appear in the piers. To be continued …

Sources: engineeringrome.wikispaces.com, pbs.org, italyguides.it