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

Local legend says Isaac Newton built this footbridge without any screws, bolts, or nails.

Unparalleled stargazing, one of Colombia's best observatories, and a swimming pool can all be found in the middle of this ancient tropical forest.

A self-taught astronomer fell in love with the stars and built his own observatory in Colombia.

With its webbed walls and bright red coloring, Calgary's iconic bridge looks like a finger trap puzzle stretched across the river.

An abandoned lighthouse awaits its destiny: being buried under shifting sand.

A historic observatory precariously perched at the "Top of Europe."

A lonely beacon, precariously perched atop a remote sliver of rock.

This old medieval prison tower has been a site of astronomical research for more than 250 years.

One of the world's oldest working clocks is curiously missing the Zodiac sign of Libra.

The world's oldest surviving anatomical theater, where "the dead are pleased to help the living."

Old vessels have been transformed into artistic canvases in this unusual cemetery.

The oceanic dumping ground where spaceships go to die.

Collection of skeletal systems from the "world's leading supplier of osteological specimens."

This Russian religious complex is a Frankenstein's chapel that includes influence from almost all the major faiths.

A clerical error gave rise to this imaginary micronation in the southwestern corner of Estonia.

This small museum is an eccentric shrine to boyhood in the 1960s.

An oddly conical beacon perched atop beautiful Irish cliffs.

A hunk of prehistoric lava rests amid the Gothic architecture of a campus quad.

Have a seat with the father of modern computing at this Manchester monument.

Dead weights honor the dead of Portugal's fishing industry.

Hidden in plain sight, this creepy sculpture watches from above.

An Oxford museum where visitors can have tea with the Mad Hatter and climb through the wardrobe to a fantasy land.

J.R.R Tolkien, C.S. Lewis, and other "Inklings" met at the Oxford pub to discuss the now legendary fantasy stories they were writing.