How did Constantine I contribute to the construction of Old St. Peter’s Basilica in Rome?

Constantine I played a pivotal role in the establishment of Old Saint Peter’s Basilica in Rome, which was begun in the later 320s CE. As part of his broader patronage to encourage the growth of Christianity, Constantine provided significant support for the project, lavishly endowing the church with property and plate.12

Architecturally, the basilica was designed as a martyrium, a structure intended to commemorate the martyrdom of Saint Peter. To facilitate the veneration of the saint's relics and accommodate the movement of the faithful, the design incorporated a large transept positioned in front of the apse. While the original structure was eventually replaced in the 16th century, it stood as one of the most significant examples of the early Christian basilica style, which adapted secular Roman assembly halls for liturgical use.3