Did You Know . . .
ROMAN LANDMARK FEATURES INNOVATIVE CONCRETE DOME

The Pantheon in Rome contains the largest unreinforced concrete dome in the world. Built by the emperor Hadrian nearly 2,000 years ago, the Pantheon’s dome was constructed long before the time of steel reinforcing rods intended to lend support and resist tensile cracking. This alone is impressive – all the more so because the inner diameter of the dome measures 142 feet or half the length of a football field. The height of the dome measures half that distance, forming one half of a perfect sphere. To make the structure lighter, Hadrian’s engineers carved depressions, called coffers, into the concrete.  They also cut a 27-foot-diameter oculus, or opening, at the top of the dome. This further lightened the load and also allows a ray of sunlight to track across the space throughout the day. 

The dome is 27 feet thick at its base and tapers to just two feet of concrete at the oculus. The Pantheon’s design combined new concrete technology with traditional Greek architecture and its construction lacked the support system that no modern architect would ever dare do without. The result is a structure that has withstood the test of time, nature and war, and remains today one of the world’s most incredible buildings. [ return to top ]