Pantheon

Built under Hadrian in 118–125 on the site of Agrippa’s earlier temple, the Pantheon pairs a traditional portico with a radical concrete rotunda, its coffered dome spanning 43.3 m and opened by a single oculus to sky and weather. Dedicated to all the gods, it was consecrated in 609 as Santa Maria ad Martyres, a change that helped it survive and turned an imperial monument into a living church. Its calm geometry, shifting light, and tombs—most famously Raphael’s—make it Rome’s enduring image of continuity between pagan, Christian, and modern worlds.