Whether you find its opulence impressive or over the top, the sheer size of the world's most important church will not leave you unmoved

Emperor Constantine built a shrine to St Peter over his tomb and near where he had been crucified in the Circus of Nero. As the fortunes of Rome and the newly established Christian religion rose and fell, the building saw periods of embellishment fluctuating with sackings and destruction, and had been much altered by the time Pope Nicholas V ordered its restoration in the mid-15th century. Work did not get under way until about 50 years later, however, when Pope Julius II appointed Bramante as the architect for a completely new basilica in 1503. Another 123 years, and interventions from many of the most important architects and artists of the time, were to pass before the new basilica was consecrated. The basic floor plan is more or less as Bramante designed it, 187m long; Michelangelo designed the 132.5m-high dome, Carlo Maderno the façade and Bernini the impressive oval colonnade that surrounds the piazza in front of the basilica.