5 Around 100 A.D., Roman builders rotated an arch in a circle and discovered that it created a strong three-dimensional shape -- the monolithic dome. They built the Pantheon and gouged the center of the dome at the top. This allowed light in the building which the Pantheon is famous for.
6 By the early 1400s, Roman engineers began building two domes in one to create the illusion of even greater height. The U.S. Capitol dome, built in 1793, gets its height from this technique. The large outer dome is a thin shell. Underneath it is a smaller, self-supporting dome, visible only from the inside.
7 A new generation of domes equipped with retractable roofs, like the Toronto SkyDome has become a popular choice for sports stadiums throughout the world. 8 Consider Union Station in Washington D.C., the Houston Astrodome, and the Gateway Arch in St. Louis. None of these structures would have been possible without the Roman arch, vault, and dome. |
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