Despite its grandiose name, this enigmatic first-century void under the town is no cave, and it's possibly not a palace either.

These primitive rock paintings include a very beloved depiction of a woolly mammoth.

The largest medieval water tank on the Iberian Peninsula is preserved beneath the Cáceres Museum.

Semi-mystical manmade towers of rocks decorate this rocky seaside.

Lava stone structures possibly dating back to the 19th century may have been a stopping point for voyagers between ancient Egypt and the Mayan Civilization.

A unique exhibit lets blind people experience famous works of art and architecture with their hands.

A whimsical garden of outsider art in the Spanish countryside.

Translating as "The Jump of the Girlfriend," this stunning waterfall has a tragic legend behind it.

Just like in Hollywood, Madrid has also a forgotten walk of fame.

Earth's rocky history has rarely glittered so brightly as it does in this Spanish museum.

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.

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

The world's largest wooden structure.

One of Europe's largest supercomputers is housed inside of a disused chapel.

Turntable anonymously received orphans, alms, and groceries.

An enchanting monastery in the Spanish countryside appears lifted from a fantasy tale.

An architect transformed this abandoned cement factory into his castle-like workshop.

Naturally formed rock city in Poland.

Buddha shrines hide within dark tunnels at this unique forest temple.

This extensive collection of dead bugs may be the world's most idiosyncratic and personal insect museum.

A "miracle" that seems to produce more holy fistfights than holy revelations.

Sitting right on the border between East and West Jerusalem this modern art museum is in itself a symbol of Israel's hoped-for unity.

This nightmarish children's plaything was left grotesque to help kids conquer their fear.

Deep in the Negev Desert, the world's tallest solar tower looks like a sight straight out of science fiction.