The keyhole of the Priory of the Knights of Malta in Rome presents a perfectly framed view of Saint Peter’s Basilica.

It’s not clear whether this is a happy accident or a deliberate design. The property lies in the piazza Cavalieri di Malta, which was designed in 1765 by the supremely imaginative Giovanni Battista Piranesi — who imagined the Aventine Hill as a sacred ship that would sail to the heavens.