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

A striking public sculpture representing the period of martial law in Communist Poland.

This amazingly well-preserved villa just outside Pompeii boasts rare examples of ancient Roman paintings.

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

This building holds the embalmed remains of the leader of the Bolshevik Revolution.

An unusual ode to the late Irish playwright, complete with a squiggly bust and coffin-shaped bench.

A brutalist gem towering over the heart of Milan.

An Austrian house of bones filled with hundreds of intricately painted skulls.

The world's oldest known salt mine.

This concrete residential area doubles as an open-air gallery.

One of downtown Berlin's last reminders of its Communist past.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

A monument to the man who almost killed Hitler.

Tiny memorials honor individual victims of the Holocaust.

One of the world's heaviest musical instruments towers within a popular urban park.

A restaurant and observation deck built in a unique broadcasting antenna.

This World War II bunker now survives as a documentation of the Nazi regime and war crimes.

A towering monument to war, located on a beautifully peaceful hill.

This Buddhist temple is home to the graves of the Japanese national legends, the 47 Ronin.

The 1852 novel "Uncle Tom's Cabin" lends its name to a subway station, a street, and several shops on the edge of Berlin.

The skeletal frame of a decommissioned gas-pumping station offers breathtaking views of greater Berlin.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

Possibly the world's largest hourglass only needs to be reset every New Year's Eve.

Known as the most scenic route in Sri Lanka, this train line is steeped in history and offers an unparalleled view of the country.