One of the main reasons to visit the Pantheon is to see its dome, which is the world’s largest unreinforced concrete dome. Even after nearly 2,000 years, it remains one of the building’s greatest features, with a perfect spherical design that demonstrates the precision of ancient Roman engineering.
At the center of the dome is the Oculus, a 9-meter-wide opening and the only source of natural light inside the Pantheon. As the sun moves, light passes through the Oculus and shifts across the marble floor and walls. When it rains, water falls straight through the opening onto the floor below, giving you one of the Pantheon’s most distinctive sights.
Why it’s a must-see: The dome’s perfect shape and the central Oculus are direct demonstrations of Roman creativity and skill.
Ticket access: Viewing the dome and Oculus is included with all Pantheon tickets.