Hadrian's Pantheon in Rome is an example of Roman concrete construction.

Outer view of the Roman Pantheon, still the largest (43.4m dia.) unreinforced solid concrete dome.

A modern building: Boston City Hall (completed 1968) is constructed largely of concrete, both precast and poured in place.

Concrete used to make a building

Concrete is an important material for making different buildings and structures. It is a composite made of Portland cement, sand, gravel or aggregate, and water. The amount of each can change depending upon what the concrete will be used for.

Concrete is used more than any other man-made material in the world. As of 2006, about 7.5 billion cubic meters of concrete are made each year—more than one cubic meter for every person on Earth.