How does a bridge withstand the forces of nature and traffic? Host David Macaulay takes viewers from the stone arch bridges of the Roman Empire to Japan's giant, all-steel Akashi Kaikyo suspension bridge, the longest in the world. Through the epic sagas of the Brooklyn, Golden Gate, and other great bridges, Macaulay shows how engineers have conquered ever-wider spans with better construction materials and innovative designs.

How does a dome support itself? Ever since the Roman Emperor Hadrian topped his Pantheon with a dome, this roof-with-class has been the prestige building form. Big domes cover civilization's most revered structures, from great cathedrals to mosques to houses of government. Host David Macaulay uncovers the tricky technology of domes, from the Pantheon to the geodesic marvels of Buckminster Fuller and beyond.

What does it take to erect a skyscraper 100 stories tall? From the medieval towers of Italy's San Gimignano to today's race to build the world's tallest skyscraper, host David Macaulay chronicles our aptitude for altitude. On the way up, he highlights the remarkable achievements of the Gothic cathedral builders and the almost-disaster of New York's Citigroup (formerly Citicorp) Center.

How does a dam resist the crush of millions of gallons of water? Host David Macaulay surveys the dam -- the biggest, costliest structure of all -- from Hoover's concrete arch confronting the Colorado River to the Aswan High Dam, a veritable underwater mountain sitting on the Nile riverbed, holding back a lake the size of England.

What keeps a tunnel from collapsing? Tunnels have advanced from dangerous, claustrophobic passages to spacious, safe subterranean networks as roomy as shopping malls. Host David Macaulay takes viewers underground to explore the history and ingenuity behind some of the world's tunneling marvels.