The perfectly preserved underground rooms where Churchill plotted the war against Germany.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

Mysterious craters may have been home to an ancient cult.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A striking symbol of the Bulgarian capital.

Destroyed Serbian army headquarters sits half crumbled in a largely revitalized Belgrade.

Nikola Tesla's ashes are held in a golden sphere, surrounded by his works.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

A stone marker and sculpture in the city of Riga stake a claim for the very first community Christmas tree.

The oldest housing complex in Riga is a mini timeline of architectural trends.

A black cat protests the City Guild in Riga's Old Town.

3,000 market stands in five former Zeppelin hangars.

The bust of Romania’s most notorious ruler, Vlad Dracula aka "Vlad the Impaler," keeps watch over the ruins of his medieval court.

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

Whitewashed mosque contains the world's largest carpet.

Northern Ireland's Brobdingnagian stepping stones.

One of England's most famous churches hides a pair of little known architectural treasures.

This skewed English house has looked like it's going to fall over for centuries.

Be on the lookout for the symbolic insect all over the city.

The rotting skeleton of a shoreside fun fair that was destroyed by fire and storms still haunts the Brighton ocean view.

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

The taxidermy remains of the first mammal ever cloned from an adult cell are on display in Edinburgh.

The most loyal of little dogs, or a Victorian era publicity stunt?

Protecting the dead from opportunistic body snatchers.