This charming Latvian lane doubled as Baker Street on the Soviet Union’s version of Sherlock Holmes.

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

3,000 market stands in five former Zeppelin hangars.

Latvia's symbolic mountain-shaped national library is home to millions of cultural tomes.

This impressively complicated radioastronomy research center was once a tool of Soviet spies.

This former Nazi labor camp is now a poignant memorial, complete with giant Soviet-style monuments.

A former imperial sea-fortress and Soviet prison.

This dizzying tower was built to better broadcast the 1980 Moscow Olympics.

A decommissioned submarine base makes a great space for graffiti art.

This medieval Italian town is a sheer (and beautiful) cliffside defense.

This serene, turquoise lake in an extraordinary nature reserve showcases a rare natural phenomenon.

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

This mysterious ancient arch is hidden in the forest of Simbruini Mountains Regional Park.

A massive bridge forms part of an aqueduct that was deemed an architectural wonder of its time.

This medieval settlement was abandoned after a series of landslides. What remained was largely destroyed during a mock battle for a WWII film reel.

What looks like a link in Gondor's early warning system is actually a centuries-old Italian fortress.

This small but lovely sinkhole lake is the last remnant of a great prehistoric water basin.

A fossil of a 30 million-year-old fish is unexpectedly hidden thousands of feet above sea level.

The tallest statue in Italy is also one of the world's tallest statues of Jesus.

Just saying the name of this town out loud is said to bring bad luck.

A medieval fountain lined with 99 unique stone faces whose origins and meaning remain unknown.

This domed temple was built in a hidden cave mouth as a refuge for sinners seeking absolution.

The remains of 50,000 World War I soldiers rest under a towering arch overlooking the Alpine battlefields.

This artistic temple brings together multiple architecture styles, but is only an example of one.