France's most famous cemetery, with some of its most curious tombs.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

An ancient instrument used to measure the waters of the Nile so Egyptian farmers would know whether to expect famine or flood.

This ancient structure is widely thought to be the oldest intact pyramid in the world.

It might not be the prettiest pyramid in Egypt, but it may be the muddiest.

One of its engravings is believed to be among the first representations of medical and surgical instruments.

The largest known Ancient Egyptian obelisk.

The Corinthian columns that towered over Abraham Lincoln’s inauguration stand proud.

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

Corn-inthian columns with a uniquely American take on neoclassical architecture.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

Fittingly, America's museum of architecture is itself a magnificently designed old building.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

It was once the base for a series of domestic terror attacks.

Home to items never before seen by the public.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.