Pantheon

The Pantheon is one of those buildings that genuinely stops you in your tracks. Nearly two thousand years old and still standing with its original dome intact, it is the best-preserved building from ancient Rome and arguably the most influential piece of architecture in Western history. The unreinforced concrete dome remains the largest of its kind ever built, and the oculus at its centre — a nine-metre open hole to the sky — floods the interior with a column of light that slowly rotates through the day. When it rains, the water falls straight through onto the slightly convex marble floor and drains away through almost-invisible holes. Originally completed around 125 AD under Emperor Hadrian, the temple was converted into a Christian church in 609 AD, which is the main reason it survived while the rest of ancient Rome was quarried for building material. It now serves as the Basilica di Santa Maria ad Martyres. Raphael is buried here, along with two Italian kings. The building sits on Piazza della Rotonda, one of the liveliest squares in Rome, and you can walk in off the street — though since 2023 there is a modest entrance fee for tourists. What makes it special is the engineering. Hadrian's architects used progressively lighter concrete as the dome rises, embedding pumice stone near the top, and the coffered ceiling reduces weight while creating a geometric pattern that draws your eye upward to that perfect circle of sky. It is a space that makes every other domed building feel like a response to it — because they are.