Pigeons are the domestic name for rock doves. They nest pretty much anywhere there are cliffs that provide rocky areas away from predators. The ideal nest spot it somewhere tucked away enough they dont need to build much of a nest. Cities are just artificial cliffs to them that killed their predators and now provide endless food. So rock doves are doing very well and have spread across the globe way beyond their native range in the middle east and northern Africa. There are huge populations in north america in the wild that never see cities.