Tools & manufacturing · c. 125 CE

Pantheon dome

A 43 m unreinforced concrete dome, still the largest of its kind.

Completed under Hadrian about 125 CE, the Pantheon used lighter aggregate toward the top and an open oculus. It remains the largest unreinforced concrete dome after nearly 1,900 years.

See it in the living tree Wikipedia

Arcs above join it to what it stood on, arcs below to what it led to. The bar places this stretch on the tree's whole timeline.

What it built on 2

Roman concrete 200 BCE
True arch 2500 BCE

What it led to 1

Brunelleschi dome 1436