Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

"Respectful to the dead, safe and sanitary to the living, dedicated to the Genius of Memory..."

One of the largest caves in the world open to the public.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

The whimsical steel spider lurking in the shadows of this suspension bridge shows that engineers can have a sense of humor.

One of the last doorless, continuously moving elevators still in use in the U.K.

A labyrinth hides in plain sight at each of the city's 270 Tube stations.

These bronze pamphlets remember a remarkable group of Germans who fearlessly opposed the Nazis in the very center of their power.

A stairway to heaven, or to nowhere at all.

A Jenga-style cylindrical tower of books that appears to go on forever.

The sign at the garden gate reads: "These Plants Can Kill."

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

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

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Skeletons dressed in extravagant 18th century royal costumes cavort in the aisles of this German basilica.

The site of a concentration camp where inmates were made to take part in one of the largest counterfeiting operations in history is now hauntingly empty.

Home to the most complete dodo remains known - one head, and one foot.

Ancient Egyptian wigs, South American feather headdresses, a bounty of anthropological artifacts in Oxford.

An array of ancient artifacts from Bronze Age Bristol and other civilizations are housed in this museum.

400-year-old garden, restored to beauty.

The names Lúthien and Beren can be found inscribed on the shared grave of the famous writer and his beloved wife and muse.

These Victorian era devil sculptures were designed to spite a local vicar.

The remains of the great moral philosopher reside in a university in London.

One fisherman has used his love of pebbles and shore to create a crazy garden of rocky art.