St. Peter's Basilica
St. Peter's Basilica is the chief church of Roman Catholicism. Situated on the Vatican Hill in Rome, it is said to have been built over the burial site of St. Peter, whose remains were allegedly discovered by archaeologists in the 1940s. During Roman times the area was held sacred by Christians, and when the Emperor Constantine came to power a large church, or basilica, was built on the site, between approximately AD 330 and 360. Though it always had an important place within the Catholic church, it did not actually become its headquarters until the 19th century, previously that position was held by the church of St. John Lateran, also in Rome. So when using the word "Vatican" to refer to the rulership of the Catholic Church, it is incorrect to do so before the 1870s, and the proper term should be "Lateran". Despite this, St. Peter's Basilica was always very important, and in 1505 Pope Julius II took the decision to demolish the now more than thousand year old building and build a much bigger new replacement. This caused much dismay at the time, and as work progressed it had profound and unforeseen consequences for Catholicism - in order to pay for it, the pope authorized the massive sale of indulgences across Europe, and this abuse of authority led directly to the revolt of Martin Luther and the Protestant Reformation. Work itself continued for over a century, and the new basilica wasn't finally completed until 1626, after many changes of design with ever more grandiose embellishments. During this time, in order to ensure continuity of services, the old basilica remained standing, and the new one, with its massive domed roof, was literally built over the top of it, an astonishing achievement for the time. Finally, amid much sadness, the old basilica was demolished, and the internal fittings of the new basilica constructed. The only thing that remains from the old structure is the altar.