The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

These "mermaids" that surround a plaza in Segovia are rather sphinx-like.

A controversial art piece that harkens back to local folklore.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

This grave resides at the crossroad of three parishes.

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

Stormy conditions send jets of seawater bursting through holes in the cliffs.

A historic Christian shrine nestled within a spectacular natural cave.

Spectacular views await visitors to this lake.

The only road through the heart of Glacier National Park.

Ruins battered by centuries of war and disaster offer a wondrous glimpse of medieval Ireland.

The ruins of a medieval monastery named after a type of tree.

This crumbling Portuguese ruin overlooks the populace it once ruled.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

"Portugal's Stonehenge" is made up of nut-like stones aligned with the heavens.

This small chapel is built of human bones and decorated with a golden skeleton.

Perhaps the most spectacular grotto along the Algarve coastline.

This unassuming chapel in Portugal plays host to a ghoulish collection of bones.

Earth's tallest volcano is sacred to Native Hawaiians, and home to a dozen world-class observatories.

This legendary urban waterfall creates a dazzling display of rainbows.

Hide from the tourist hordes in these relatively unknown, and unguarded lava caves.

These ancient sacred grounds granted amnesty to those who managed to reach them.

A controversial memorial at the place where Captain Cook met his violent end.