The National Park Service’s best-kept secret with views that rival any in D.C.

"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!”

Look closely and you’ll notice that the color changes a third of the way up the tower.

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

Largest Roman Catholic church in North America.

An ancient iron pillar in Delhi that seems to be rustproof.

A blooming house of worship for the masses.

At the top of the hour, this steam-powered clock's eight brass whistles play "Back Home Again in Indiana."

Inspired by a piece of concrete, these three pyramid-shaped buildings have been beloved Indianapolis landmarks for over 50 years.

Once adorning a New York skyscraper, these reclaimed ruins now haunt an Indiana park.

This icon of the Atomic Age now lays dormant.

There aren't too many operational funiculars around, but Pittsburgh has two!

The only way to see Pittsburgh is from the top of this lookout point, just like the ancient members of the native peoples did.

The United States’s oldest funicular railway glides up and down a steep Pittsburgh street.

Secret North Korean passage discovered below the world's most dangerous border.

Traditional 11th-century outdoor tannery.

An awe-inspiring mosque in Morocco with one of the tallest minarets in the world.

World's largest film studio, where visitors tour the decaying sets that litter the harsh desert environment.

One of Europe's largest supercomputers is housed inside of a disused chapel.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Built on the remains of one the Incas’ most important gathering spots, this square keeps the spirit of a fallen empire alive.

Situated on a sacred Inca site, this 16th-century cathedral took nearly 100 years to build.