Here’s an interesting study of how Christianity gradually took over the suburbs of Rome, beginning in the third century. “During the mid-Imperial period this area was characterized by a complex system of roads, residential districts, farms, and funerary monuments. Starting from the late second century, it was increasingly devoted to the creation of ‘Christian spaces,’ first in the form of surface and subterranean funerary complexes, and later with churches and monuments associated with the presence of the martyrs’ tombs. In the fourth and early fifth century, the presence of Christian cemeteries, between the Aurelian Wall and the third milestone, contributed also to the growth of secondary access roads to the funerary complexes.”

I guess you could call that urban renewal.

The article, “The Christianization of Space along the Via Appia: Changing Landscape in the Suburbs of Rome,” is by Roman archeologist Lucrezia Spera, and it appeared (well illustrated) in the American Journal of Archaeology. You can download it for free right here.