The grand, column-fronted, sculpture-adorned home of the ambitious digital library.

This stunning natural double arch, the largest in the Alps, went undiscovered until 2005.

Lived-in building, bedecked with an astonishing array of mirror mosaics.

One of the largest-ever mental hospitals now sits abandoned, surrounded by 25,000 unmarked graves.

The reason for the strange contortions in the trunks of these "drunken" pine trees in Russia is still a mystery.

A plaque marks a former safe house on the secret route, now hidden next to a McDonald's.

A hidden barn-sized rendition of Grant Wood's most famous, and most parodied, painting.

An abandoned mine now resembles a post-apocalyptic landscape of derelict buildings and blood-red pools of water.

The world's largest banyan tree is followed by a community of worshippers.

This abandoned fishing settlement may well be the greenest village in the world.

A luxuriant botanical garden below sea level.

A marvel of Byzantine engineering under the streets of Istanbul.

Remants of foundations, streets, and streetcar tracks inhabit the cliffs where a landslide occurred in 1929.

More than half of this Indian palace is drowned but it looks all the more spectacular for it.

Plenty of old carney magic still haunts this photogenic amusement park.

A pair of large white marble lions guard this stretch of the Mojave Desert, and it is utterly mysterious how they got there.

Tubing through a cave lit with glowworms is a magical underground experience.

A solitary tree has grown up all alone on Lake Wānaka, backdropped by the beautiful Southern Alps.

The once and future home of New Zealand's famed Pink and White Terraces.

Medieval irrigation channels built into the sides of mountains provided Valais with water for hundreds of years.

This natural wonder drops 16 stories straight down through rare flora and streaming waterfalls.

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

A collaboration of art and ornithology mourns the calls of Sydney's lost birds.

A Texas cave network is home to some of the world's most spectacular-looking and bizarrely named mineral formations.