The catacombs that lie beneath the Igreja de São Francisco have to be Porto's most macabre attraction. In the view here we can see the walls are lined with the crypts of wealthy local families. If you look down you can see each rectangle on the floor is a further tomb with a number, but no name. Apparently this is because these were only temporary graves and after a while the body was removed to make way for another paying customer.
In case you are wondering what happened to the bodies once they'd outstayed their rent you'll find the answer around the corner. A window in the floor looks down on a large pit filled with countless bones.
