Cathedral Basilica of Saints Peter and Paul, Philadelphia

This beautiful cathedral is the centerpiece of one of the largest Catholic populations in North America. The foundation was dedicated June 29, 1846 and construction was finished in 1864. With its beautiful baldachino dome over the altar, it's a prime example of the Italian Renaissance style. It's also the oldest building on the Parkway–which makes sense, since the Parkway was not constructed until 1925.