One of the largest trees of its kind in California.

Originally built for London’s cab drivers, this bright green hut now serves anyone a hot drink or meal.

This grand old 80-foot sequoia towers above the buildings in the city’s retail center.

This hidden sculpture garden full of Wild West art is one of San Antonio's best-kept secrets.

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

A mysterious plaque to the even more mysterious "Fr. Pat Noise," killed in "suspicious circumstances."

The mastermind behind this palatial hotel perished on the Titanic weeks before its grand opening.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

The most decorated dog of World War I is preserved in the Smithsonian.

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

The house where John Wilkes Booth conspired with his co-conspirators.

Legend has it the commander of the defenders drew a fateful line in the dirt with his sword just before the final battle.

One of the oldest used bookstores in the U.S. has been selling antiquarian treasures since 1825.

Clap your hands at the base of the pyramid, and the song of a sacred Mayan bird will echo through the air.

The library's graceful rotunda is like a bibliophile's temple.

Sweden's oldest animated sign is still lighting up the skyline today.

This Stockholm light tower can be controlled by anyone with a smartphone.

Now a hotel, this former bank was the site of a robbery that spawned a psychological phenomenon.

Early habitat dioramas and home of the elusive gaff, the skvader.

A hidden bathhouse in one of Stockholm's oldest and busiest neighborhoods is open to anyone who can find it.

The world's largest model of our planetary system.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

It houses the remains of a 17th-century version of the Titanic.

A golden plaque marks the site of the mysterious unsolved assassination of the former Swedish prime minister.