The Popes rebuilt Rome during the Renaissance, creating massive basilicas like St. Peter's, funding amazing sculptures and paintings, and importing expensive marble and precious metals. But Rome was not a rich city. Where did they find the money?

A major source of funding for St Peter’s in particular, at least in the initial stages, was one of the most significant sore spots of all European and even world history: the sale of ‘indulgences’, or supposed relics of Biblical or saintly importance (eg, a skull alleged to be of some saint, or an item mentioned in the Gospels, even pieces of the cross) whose purchase would grant the buyer a certain number of years off their time in Purgatory. A rather notoriously aggressive salesman and friar, Johann Tetzel, was instructed by the Archbishop Albrecht of Mainz to scour Germany and raise funds through preaching and selling various such relics, the funding of St Peter’s being the main incentive, and he was very effective. And it was in reaction to precisely this that Martin Luther’s wrote his 95 theses, or ‘Disputation on the Power and Efficacy of Indulgences’, and sent them to the same Archbishop of Mainz in protest. Whether he actually nailed them to the door of All Saints’ Church in Wittenberg is not known, though nailing them to church doors was at least discussed. Many take this to be the birth of Protestantism, though Luther’s views were not fully formed and at this point he still believed that the Pope agreed with him, perhaps failing to realise that these methods were at the Pope’s behest. But it was certainly the first major step that sent him down the path that became the Reformation.

But this was not the only funding that was available, at all. St Peter’s took over a century to build, only being consecrated in 1626, so there were many methods drawn upon. The papacy formally ruled a quite large middle belt of Italy, the Papal States, and could raise taxes from them, though tax increases were usually not welcome (!) and could meet resistance. In fairness, unlike many other states of the era, they did not mostly spend it on wars (though with their involvement in the Castro wars against a pope’s family’s rival dynasty, and their leading leagues in some of the Italian Wars, the Popes were far from above doing so), but rather on supplying and distributing food to the people, as well as buildings. The Papal States were far from impoverished. The commissions given to artists show that even if the Rome of the era was certainly not a rich city by today’s standards, but in the High Renaissance context it would be a bit strange to call it ‘poor’.

This was the Papacy’s secular authority. But it also, on occasion, demanded income taxes from the clergy across Europe: this being first raised in 1199 for the Crusades (or rather upkeep of the defence of the Crusader states between the 3rd and 4th, rather than for a crusade per se), and then more regularly after the Fourth Lateran Council of 1215, but a very small amount.

It was also far from uncommon for major donations to be made to the church from all over Western Christendom out of piety (or guilt), including from the wealthy and powerful, especially with the culture of indulgences that had developed.

Finally, the Renaissance era saw the flourishing of some modern aspects of banking. The Medicis were the most famous of their time, and had the great honour of being the Pope’s bankers, and the papal account was for a long time their largest. This is hardly the sign of poverty. The Pope in 1517, Leo X, when Luther reacted to Tetzel’s methods, was in fact himself a Medici (and not the only one in that era), which was a great boon for the Medicis but an even more reliable connection to funds for the Church. Even when the Pope was not a Medici, on occasion they were pressed to make the Pope a very large loan, and in fact the Pope had a massive overdraft for a large proportion of the lifetime of the account, another source of ‘income’ of a kind. The Pope was granted more leniency than others because of the status of being the Pope’s bankers, as well as the authority he had over religious matters: the threat of excommunication was no joke, either for the religious or for the secular (since this could easily be used as justification by rivals and jealous rulers of other lands they operated in to seize their other assets). So arguably through ‘soft’ power as well as religious and social blackmail (if that’s not too loaded a word), or simply by themselves being members of it, the popes had an enormous line of credit from the richest family in Italy.

All of these sources could be called upon, and the cost was enormous but over the century plus of St Peter’s construction, eventually borne.