The baptistry is the largest in Italy, and like its tower companion, it tilts as well. Again locals will say it was a mistake, but most experts agree it was built by those crazy Pisanos on an intentional tilt. Both the tower and the baptistry were built in the 12th century, with the cathedral about one hundred years earlier and the Campo Santo one hundred years later. This building boom coincided with Pisa's peak in power and riches, before it got whacked on all sides by its neighbors and Mother Nature, as you'll read about later.