The story of Old Saint Peter's in the fifteenth century is dominated by the plans that Nicholas V laid for the basilica's modernization. The pope's biographer, Giannozzo Manetti, described his ambitious scheme to remodel Saint Peter's and its surroundings as part of a larger campaign to improve both the symbolic and practical effectiveness of Rome's urban environment. The powers of the cardinal archpriests of the papal basilicas depended at least to some extent on their relationship with the pope, as they deputized on his behalf. The duration of Pietro Barbo's formal relationship with Saint Peter's was exceptional. His tenure as cardinal archpriest outlasted the popes whom scholars have most closely associated with the basilica's fifteenth-century redevelopment. While Barbo directly commissioned a group of monuments and altars that commemorated his family, he also had overall responsibility for the basilica's day-to-day business.