The Pantheon is my favorite building in the whole wide world. I love the rotunda (still the world’s largest unreinforced concrete dome), its oculus open to the sky (letting in a moving circle of sunlight or rain), originally intended as a ventilating escape for the smoke from animal sacrifices below. Commissioned by consul Marcus Agrippa circa 27 BC as a temple to all the ancient Roman gods, it was rebuilt in 126 AD by the emperor Hadrian to pretty much its present structure. I love that back in the 1980s, I would pass by on my Roman wanderings, step inside and be the only person within its cavernous interior. (Not the case during my most recent visit; there are now guard rails to shepherd the tourist crowds in and out in an orderly fashion.) It still functions as a church (which it has been since the 7th century); there are several altars, the tombs of Raphael and Italian kings Vittorio Emanuele II and Umberto I and his queen Margarita (of pizza fame.) Regular recorded announcements in several languages urge the noisy throngs to remain silent in this “sacred place.” No such luck.