Largest Roman Catholic church in North America.

Island ghost town detailing Flagler's folly in building the Overseas Railroad.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

Pop culture has helped to keep this iconic British building from being destroyed.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

A grand Gothic Revival basilica with stained glass depictions of Montreal's religious history has only one soul resting in its crypt.

Every equinox this Maya pyramid puts on a spooky ancient light show.

Visitors can walk over the largest concentration of Columbian mammoths to have died from one event.

Named the fifth most beautiful building in America in 1885, this former courthouse boasts the best view in the Village.

Nestled in the heart of San Francisco’s bustling Financial District stands a unique homage to the Mayan and Beaux Arts.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

A wall of chewing gum moonlights as collective art.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

The seawater playground of gilded-era San Francisco burned to the ground in 1966.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

A 200-year-old bar in the historic French Quarter refuses to give up its place in history, nor its role in securing ours.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

A dark patch of the ceiling at Grand Central Terminal which was not restored is still stained brown by tobacco.

A 400-foot-tall tall map of Chicago makes this once-ignored building stand out.

A building so large that it has its own weather.