Fifteen hundred years ago, the emperor of Rome built a tomb for his beloved sister. The small building was designed in the shape of a cross with a vaulted ceiling covered with mosaics of swirling stars in an indigo sky. The focal point of the mosaic ceiling was a depiction of Jesus as a shepherd surrounded by sheep in a green paradise.
The mausoleum of Galla Placidia still stands in Ravenna, Italy, and has been called by scholars "the earliest and best preserved of all mosaic monuments" and one of the "most artistically perfect."
But visitors who have admired the mosaic in travel books and on postcards will be disappointed when they enter the mausoleum. The structure has only tiny windows, and what light does enter is usually blocked by a mass of tourists. The "most artistically perfect" mosaic monument, the inspiring vision of the Good Shepherd in a starry paradise, is hidden behind a veil of darkness.
But those who are patient, who endure the musty darkness and claustrophobia, will be rewarded. With no advance notice, spotlights near the ceiling are turned on, illuminating the iridescent tiles of the mosaic, but only for a few seconds. One visitor describes the experience: "The lights come on. For a brief moment, the briefest of moments—the eye doesn't have time to take it all in, the eye casts about—the dull, hot darkness overhead becomes a starry sky, a dark-blue cupola with huge, shimmering stars that seem startlingly close. 'Ahhhhh!' comes the sound from below, and then the light goes out, and again there's darkness, darker even than before."
The bright burst of illumination is repeated over and over again, divided by darkness of unpredictable length. Each time the lights come on, the visitors are given another ...