Cross-section illustration helps convey the scale of the Pantheon.

An illustrated cross-section helps convey the massive scale of the Pantheon. The foundations are 24 feet (7.3 m) thick at the base and stepped back to 21 feet (6.4 m) at ground level. The interior fluted columns are 3 feet (0.9 m) in diameter by 29 feet (8.8 m) tall, topped with a 4 foot (1.2 m) tall Corinthian capital — totaling 33 feet (10 m) tall at 25 tons (22.7 t) each. And the Portico has 16 granite columns, 5 feet (1.5 m) diameter by 39 feet (11.9 m) tall weighing 66 tons (60 t) each.

David Collins