This historic black and white monastery is one of Bulgaria's architectural jewels.

"Holy Wisdom" overlooks the city that became its namesake.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

An homage to the medieval rulers of Bulgaria.

A decaying, yet still functioning, work of communist architecture.

Conspiracy theories and occult legends surround this mysterious natural rock formation.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

This snug medieval lane is one of the narrowest streets in the world.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

Plaques celebrating Lithuanian writers freckle a wall of this picture-perfect path.

Legend has it that Napoleon Bonaparte fell in love with this Gothic church.

The site of London’s first coffee house has been serving refreshments of one kind or another for 360 years.

The last four extravagant street signs of London's historic banking street.

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

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the first ‘Harry Potter’ film.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

London's smallest police station is barely the size of a phone booth.

This tiny alleyway is now a shrine to a subculture riot between the mods and rockers.

These shopping center benches are actually a modern art installation.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

This 1920s Dutch barge is now a floating bookstore.

Never actually a tree at all, this spot was the site of London's public hangings for nearly 600 years.