Pantheon and Sant'Ignazio: the Real Dome and the Painted One

Two churches a few minutes apart, and the pairing is the point: one has a dome with a hole in it, the other has a dome that does not exist. At the Pantheon the guide covers how a pagan temple became a Christian church and then a royal mausoleum, which gods it was dedicated to and on whose orders. The dome overhead is still the largest ever built in concrete, and the open eye at its centre is the only source of light in the room. Around the wall are the tombs: the painter Raphael, King Victor Emmanuel II and Queen Margherita. Then the church nearby, where the ceiling is painted so that the architecture appears to carry on upward into open sky, and where the dome you are looking at is a flat canvas. There is a marked spot on the floor from which the illusion works, and the further you walk from it the more visibly the whole thing collapses. It was painted that way because the real dome was never built. Seeing them in this order is worth arranging. The Pantheon solved the problem; the other church painted its way around it.