Drum, dome and lantern of St. Peter's Cathedral, Michelangelo; continued by Giacoma della Porta and Domenico Fontana Vatican, Rome (Italy)

Renaissance Rome had more Early Christian and Medieval churches per head than any other city in Europe.  Just to maintain this legacy was such a drain on papal resources that few new churches were built in the first three-quarters of the fifteenth  century.  But with the revival of humanism and classical culture, new ideas of church design emerged which made earlier churches appear to be inadequate expressions of both Christian doctrine and papal ideology.

The mid-fifteenth-century renovation of St. Peter's was the first important Roman Renaissance church designed with reference to classical architecture.  It was almost certainly influenced by the treatise, On the Art of Building (1452), written by Leon Battista Alberti (1404-72), which advocated that the dimensions and plan of any church symbolize the heavenly Jerusalem and be conceived according to simple mathematical ratios and clear geometrical forms.

Plans for Renovations to St. Peter's Basilica (early 4th Century - early 17th Century)

The plans for the new St. Peter's went through many stages.  The spiritual and pilgrimage center of the church was thus transformed into a chaotic construction site and would remain so for the next one hundred and fifty years before it was finally completed.  The two most important architects to work on the redesign of St. Peter's included Michelangelo and Bernini.

Finally, in 1626, one hundred six years after its inception and 1,300 years after the consecration of Old St. Peter's, the new basilica was consecrated by Pope Urban VIII Barberini (reigned 1623-44).  The finished form of St. Peter's, through all the multiple transformations of its building and design history, makes it seem like the work of a single mind.