Pantheon Rome

Modern Engineers Still Cannot Fully Explain How the Pantheon’s Dome Has Held for 1,900 Years

The concrete dome was poured around 125 CE. At 43.3 metres in diameter, it was the largest concrete dome ever built, a record it held for over 1,300 years until Brunelleschi’s Florence Cathedral dome. No steel reinforcement. No significant repairs in nineteen centuries. The concrete mix uses progressively lighter aggregate as you ascend – pumice near the oculus, denser material at the base – reducing weight in a way that modern structural analysis confirms was precisely calibrated. The question of how Roman engineers understood the mechanics of this without modern materials science remains genuinely open.

The oculus at the top is 8.2 metres wide and is the building’s only light source. When it rains, the rain comes in. The floor drains carry it away. The interior holds a perfect sphere: the distance from floor to oculus equals 43.3 metres, precisely matching the dome’s diameter. The Colosseum gets longer queues. The Trevi Fountain gets more coins. The Pantheon is the most technically extraordinary building in Rome.

Visiting in 2026

Tickets cost EUR 5, rising to EUR 7 from July 1, 2026. The extra EUR 2 is earmarked by Italian law for a state programme supporting libraries in disadvantaged communities – an unusual destination for archaeological site revenue. EU citizens aged 18 to 25 pay EUR 2. Under-18s and Rome residents enter free. The first Sunday of each month is free entry.

All tickets are nominative: the name on the booking must match government ID exactly. Modifications require 72 hours’ notice. Book timed slots online for peak season (July and August, with 10:00 to 14:00 being the most crowded hours). The building opens at 09:00 and morning light through the oculus – a beam that tracks across the interior as the sun moves, falling on the entrance corridor in a way that appears intentional – is the best reason to arrive early.

The Pantheon is still an active Catholic church. Sunday masses restrict tourist access.

Who Is Buried Here

Raphael is buried inside the Pantheon, in a niche to the left of the main axis. King Vittorio Emanuele II, first king of unified Italy, is also here. Both tombs are understated and easily missed while everyone is looking at the dome.

The Neighbourhood

Piazza della Rotonda directly outside has overpriced restaurants and gelato. Skip them. Walk four minutes west to Gelateria Giolitti on Via degli Uffici del Vicario (open since 1900). Walk ten minutes north to Sant’Eustachio il Caffe for what is consistently ranked the best espresso in Rome – beans roasted on site, a specific preparation method, EUR 2 at the bar standing up. Sitting outside costs more and misses the point.