One of the most horrifying sights in all Christendom, this is a series of chapels with hundreds of skulls and crossbones woven into mosaic "works of art." To make this allegorical dance of death, the bones of more than 4,000 Capuchin brothers were used. Some of the skeletons are intact, draped with Franciscan habits. The creator of this chamber of horrors? The tradition of the friars is that it was the work of a French Capuchin. Their literature suggests that you should visit the cemetery while keeping in mind the historical moment of its origins, when Christians had a rich and creative cult for their dead, and great spiritual masters meditated and preached with a skull in hand. Those who've lived through the days of crematoria and other such massacres might view the graveyard differently, but to many who pause to think, this sight has a message. It's not for the squeamish, however. The entrance is halfway up the first staircase on the right of the church.