The Pantheon is the centerpiece of Piazza Della Rotunda in Rome, Italy. Its origins are clouded, but there is general agreement that the building in its present form dates from between 100 - 200 AD. Originally constructed as a Roman temple, the Pantheon has been used as a Catholic church since 609 AD. For an ancient structure it is remarkably well-preserved, probably owing to continuous use throughout its history.
Most of the stone cladding that used to adorn the exterior of the building has been removed, leaving a rather crude façade exposed to the piazza. It is the interior of the building, however, that truly delights. A large, open oculus is situated at the apex of the domed ceiling. It admits the exterior elements to the interior space, rendering it as a sort of threshold experience - neither inside or outside - both sacred and profane.