This 47-story "M" needed 20 years to be completed

This surreal-looking tree pruned more than 1,000 years ago is still producing olives for oil.

A huge cathedral single-handedly constructed by one eccentric monk.

A breathtaking and biodiverse wilderness in the mountain setting of Ernest Hemingway's "For Whom the Bell Tolls."

A contemporary art installation housed within a Gothic cathedral.

Seaside ruins of a settlement that date back to the first century B.C.

This enchanting hamlet carved into the rock looks like something straight out of Tolkien's Rivendell.

One of Antoni Gaudí’s earliest buildings, built between 1886 and 1890 for the industrialist Eusebi Güell.

An out-of-place grove of sequoias thrives in northern Spain.

Catalonia Tradition: Beating the hollow Christmas log until it defecates in your fireplace.

This awesome Spanish castle is so fantastical it was actually used on Game of Thrones.

Commonly acknowledged as the only public monument to the Devil himself.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

A stately palace has been converted into the world's largest cannabis museum.

Bacteria and algae give the salty water its bubblegum hue.

The oldest restaurant in the world is this old-world Spanish eatery, still known for its suckling pig.

Abandoned for over a century, this chilling train tunnel is now a destination for ghost hunters.

The first outlet of Canada's biggest fast-food franchise has been slinging doughnuts since 1964.

A small memorial commemorates a man who died at Kilkee Cliffs.

This center tells the story of one of the most famous battles in Irish history.

At the time of its construction, this hydroelectric power plant was the largest in the world.

This memorial was created by an Irish nurse who lived in New York City during 9/11.

The symbolic center of Ireland, this summit also offers panoramic views of the countryside.

This Copper beech tree nestled on a nature reserve is host to a bevy of autographs from Irish literary icons.