Originally constructed as a mausoleum in the second or third century CE, this secular structure was later converted into a church and dedicated to the Virgin Mary. In the early sixteenth century, it was incorporated into the new basilica of St Peter, which Cornelis van Poelenburgh has eliminated to more fully articulate the building as an ancient Roman one. A Dutch artist present in Rome between 1617 and 1625, Poelenburgh often reduced details and eliminated modern components in his Roman sketches to create powerful studies in pen and wash.