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

America's original house of worship for Spiritualism, the religious movement based on communing with the dead.

These sacred Mesoamerican ruins feature peculiar petroglyphs hidden in the stones.

These barriers stand as stark reminders of Northern Ireland's troubled past.

It was once nicknamed "the most bombed hotel in Europe."

This neon landmark has been posing this deadpan question to follicly-challenged Dubliners for over 50 years.

The 19th-century pharmacy (now a used bookstore) was featured in James Joyce’s "Ulysses," and has changed very little to this day.

One of Ireland's most infamous prisons for rebels including men, women and children.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

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 was finally completed in 2026—a century after the death of its architect.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

If you can look past the nearby sewer pipes, this urban sinkhole grotto is a mini-paradise.

These azure waters were thought to lead to the Mayan Underworld.

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

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

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

An elaborate Mayan city shrouded in alien conspiracy revealed the tomb of Pacal the Great.

The stoutest tree in the world.

This beautifully deceptive waterfall is something far different from what it appears to be.

An Aztec temple, the largest man-made pyramid in the world, sits buried in earth with a Spanish church set on top.