ST. PETER'S, the Cathedral of Rome, the largest and one of the most magnifi cent churches in Christendom. It is a cruciform building in the Italian style, surmounted by a lofty dome, built on the legendary site of St. Peter's martyrdom. In 306 Constantine the Great erected on this spot a basilica of great magnificence. In the time of Nicholas V. it threatened to fall into ruins, and he determined on its reconstruction, but the work of res toration proceeded slowly, and Julius II. (1503-1513) decided on the erection of an entirely new building. He laid the foun dation stone of the new cathedral on the 18th of April, 1506, and selected the fa mous Bramante as his architect. After the latter's death various architects had charge of the work till Michelangelo was appointed in 1546. He nearly com pleted the dome and a large portion of the building before his decease (1564). The nave was finished in 1612, the facade and portico in 1616, and the church was dedicated by Urban VIII. Nov. 18, 1626.
The extensive colonnade which surrounds the piazza and forms a magnificent ap proach to the church was begun by Ber nini in 1667, and the sacristy erected by Carlo Marchionni in 1776. The interior diameter of the dome is 139 feet, the ex terior diameter 1951/2 feet; its height from the pavement to the base of the lan tern 405 feet, to the top of the cross out side 435 feet. The length of the cathedral within the wails is feet; the height of the nave near the door 1521/2 feet; the width feet. The width of the side aisles is 33% feet; the entire width of the nave and side aisles, including the piers that separate them, 197% feet. The cir cumference of the piers which support the dome is 253 feet. The floor of the cathedral covers nearly 5 acres, and its cost is estimated to have exceeded $50, 000,000.