Dome History

Throughout history, domes have been covered some of the most important buildings. Because of their shape, domes are some of the strongest and stiffest structures that can be constructed.

The super strong dome shape exists in nature in the domed shells of turtles. Ancient builders copied the shape in tent like structures. Sometime around 100 A.D., Roman builders discovered that if they took an arch, and rotated it in a circle, they could create the strong dome shape. The invention was revolutionary, and soon they were using stone domes to cap their most important buildings.

The Pantheon Dome

The first masonry dome was the Pantheon. Built by Emperor Hadrian, to demonstrate the power of his empire, the Pantheon is built of brick masonry and concrete. The Romans cut recesses, known as coffers, into the inner face of the dome, to reduce the enormous weight of the structure. At the top of the Pantheon dome they left a hole, called an oculus (from the Latin word for eye), which allows a dramatic beam of light into the interior. The oculus is open to the weather and rain that enters is collected by floor drains. Almost 2000 years old, the Pantheon still exists today.

Mihrimah Dome

As domes grew taller, they became heavier. Around 530 A.D., dome design was again advanced when ancient engineers began adding openings to domes between the arches. This new design lightened the weight and allowed sunlight into the dome. The Mihrimah Mosque, built by the architect Sinan, in 1555, has arches with window glass infill walls in the sides of the dome.

The Dome at St Peters Basilica

In 1506 Pope Julius II, hired Italian architect Donato Bramante to crown St. Peter's Basilica, the main church at the Vatican, with a dome. The church had outgrown the old Basilica. Bramante's vision for the Basilica was a cross with equal-sized arms around a central dome. But both Pope Julius and Bramante died before much construction could be done. Control of the project was given to a brilliant young artist from Florence named Michelangelo. Michelangelo's design was giant dome, rising 450 feet and 138 feet in diameter. To contain the outward thrust of the heavy masonry dome, three iron tension rings were built into the dome.

The U.S. Capitol dome.

The Capitol dome is one of the first domes made with thin, prefab construction.

The Capitol is actually two domes, an inner dome and an outer dome. The large outer dome is a thin shell, supported by a ring of curved iron ribs. Below that is a smaller, inner, self-supporting dome. Built in 1863 by architect Thomas U. Walter, the domes thin shell construction was prefabricated components, paved the way for later prefab dome construction.