Legend says this sacred tree was a gift from goddess Athena.

A marvel of Byzantine engineering under the streets of Istanbul.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

Bullet holes in the church wall are a reminder of the violence that followed the assassination of a high-ranking Nazi officer.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

An extensive collection of reliquaries containing the bones of saints housed in the largest Catholic church in Venice.

Go inside to really appreciate this 500-year-old technological masterpiece.

Two stone columns flank the grand Venice square, but there were supposed to be three.

Ancient snack bar of the Roman Empire re-opened.

Pilgrimage site for star-crossed lovers.

The fairy tale castle of the "fairy-tale king."

Asthmatic Charles Hyett's son built a fantastical garden for his father to convalesce in, alas it was too late.

The only medieval bridge in Britain with its defensive tower still in tact.

This pub can leave even the sober feeling slightly unsteady.

This bridge is the first to be made entirely from iron, but designed like it was still made of wood.

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

This stunning concert hall has become a symbol of Iceland's national recovery.

Medicinal spa created with the discharge from a geothermal energy plant.

The picturesque birthplace of Icelandic democracy is drenched in the blood of its brutal past.

A formerly glacier-tipped volcano that inspired none other than Jules Verne.

5,000 skulls in memorial to those killed by the Khmer Rouge.

One of the biggest markets in Asia, under one of the continent's largest domes.

Khmer Rouge's high security prison.