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Pantheon
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Vital Statistics:
Location: Rome, Italy
Completion Date: 123
Diameter: 142 feet
Type: Ribbed
Purpose: Religious
Materials: Concrete, brick
Architect: Hadrian

When Roman Emperor Hadrian decided to build a monument to reflect the power of his empire, he built a dome -- but not just any dome. Hadrian constructed a building out of bricks and concrete with a dome that was bigger and more extraordinary than anything anyone had ever seen before. The enormous building, called the Pantheon, was built as a temple to all the Roman gods almost 2,000 years ago. It still exists today, almost entirely in its original form.

Pantheon
Click photo
for larger image.

The Pantheon is remarkable for its size, its construction, and its design. The enormous dome stretches 142 feet in diameter; that's the same as the distance from the Statue of Liberty's sandals to her torch! Given the dome's size and weight, Hadrian's engineers had to find ways to lighten the heavy structure. They scooped out 140 waffle-like depressions, called coffers, in five rows around the dome's base to eliminate some masonry and reduce the dome's weight. They also carved an opening, called an oculus, at the top of the dome, which reduced some mass and created a daily light show for which the Pantheon is famous.

The result was an impossibly huge dome, one that would remain the world's largest for 1,300 years.

Here's how this dome stacks up against some of the biggest domes in the world.
(diameter, in feet)

Chart showing the relative size of the biggest domes in the world Pantheon
142'

Fast Facts:
  • Pantheon is a Greek word meaning "to honor all Gods."
  • The oculus, or "eye" of the dome, is 27 feet wide -- five teenagers could stretch across the hole!
  • At its base, the dome is 23 feet thick, but only two feet thick at the rim of the oculus.

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