This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

Elaborate tile work in this railway station tells the story of Portugal.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

Seat of the Duke and Duchess of Devonshire for centuries.

A stone obelisk towering over the surrounding countrysides beckons hikers across the rolling moors.

Collapsed television tower finds new life as a control tower for boat races.

Fascinating town where normal life interfaces with the occult.

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."

The somber sculptures commemorating Irish Famine on the river Liffey in Dublin.

Amidst the bustling streets of Dublin, there is a hushed garden that is dedicated to "All those who gave their lives in the cause of Irish Freedom."

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.

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

19th century museum with an eclectic mix of curiosities, from Egyptian artifacts to items on archery history to the skull of the world's oldest horse.

Artifacts and memories from the Vietnam war, located in a place that experienced it first hand.

The lavish temple of the Cao Dai religion that includes Buddha, Mohammed, Joan of Arc, and Victor Hugo.

A nightmare for the claustrophobic lies hidden in Southeast Asia.

A musical instrument played by the sea.

This one-time health resort was used by aristocrats around the world.

This massive subterranean fissure is known as the "underground Grand Canyon."

In this historic region, homes and churches are carved into ancient volcanic rock formations.

The oldest known university in the world is in Fez, Morocco.

The other side is actually green.

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