One of the unique sights of Old San Juan is Parque de las Palomas. Most cities consider pigeon to be pests, but in San Juan they built a park to be home to them. Pigeons are know as rock doves, and they nest in the small crevices in cliffs. In this park its creators built cubby holes into the side of a building to make the birds feel at home.
Families come, and there are machines that sell bird feed. If you stand real still and put some feed in your hand, the doves will come and eat.