The first tunnel to be dug beneath a river, repurposed as an art and museum space.

This London marker celebrates the spot where the world-famous English band was founded.

This tribute to the fictional detective stands at the famous literary character's address.

A display of everyday life in the area that was unveiled during the 2012 Summer Olympics.

This life-size monument honors the legacy of a famous literary feline.

This hydraulic power system in London was, at one time, seen as a rival to electricity and the last of its kind to shut down.

This mysterious pyramid is said to be part of a complex web of occult and Freemason symbols.

The remains of the debtor’s prison that shaped Charles Dickens’ life and writing.

A scenic UNESCO site that doubles as a habitat for various forms of wildlife.

This 19th-century pub features stained-glass windows celebrating Victorian-era “champions.”

An ornate and disused early 20th-century building has been given new life as a fully operational structure, complete with offices, oyster bar, and a furniture retailer.

It’s a painted window that looks completely real, hiding on a building in the market square.

This ex-prison dates back to the Middle Ages.

In the center of Wrocław's old meat market stands a somber tribute to the city's livestock.

The silly symbol for an underground protest group is now scattered around the city.

An unfinished Serbian Orthodox church with 1,389 golden crosses planned to represent the Battle of Kosovo.

A futuristic, brutalist masterpiece that is also strangely prison-like.

This massive monument was unveiled the day Kosovo declared independence from Serbia.

Backwards hour and minute hands and a timing mechanism that fluctuates with the temperature led to this clock tower's local nickname.

Belgrade’s oldest restaurant has a rather unusual name.

Arguably Belgrade's only example of pure Art Deco architecture.

A towering spire in the fortress of Kalemegdan honors the victorious armies of Serbia during their struggles against the Ottoman Empire.

This small bronze pyramid marks the center of Belgrade, but some say it is a Masonic symbol.

A portly statue of a golden boy commemorates an unusual cause of the Great Fire of London: the sin of gluttony.