This antique thermometer honors the creator of the first universal temperature scale.

The site of the first battle of World War II.

This fairytale inspired, warped building houses restaurants, shops, and a radio station.

This Nazi ruin was the site where Hitler was almost blown up by a suitcase bomb.

Built to transport German U-boats through the never-completed Masurian Canal, the locks near this Polish village are now home to a rope course.

The two abandoned overpasses are among the largest bridges in Poland.

An extensive collection of some of the oldest grave markers in Lithuania.

Lithuania's outdoor sculpture trail of wooden folk art.

The mile-long pier stretches from a ruined fortress out into the Baltic.

These crumbling Latvian forts make for some haunting seaside ruins.

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

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

3,000 market stands in five former Zeppelin hangars.

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

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

Flamboyant architecture from the turn of 20th century.

A former Latvian headquarters of the brutal KGB secret police is now open as a grim reminder of their atrocities.

This statue is dedicated to the animal cosmonauts that perished during space flight experiments.

This Estonian watchtower looks like a big tree with two giant bird nests on it, complete with a "golden egg."

Man-made mineral caves house massive bat colony.

The first designer power line in Estonia.

Mysterious craters may have been home to an ancient cult.

Once standing on solid ground, this slender beacon is a victim of the very shoreline it was charged with announcing.

Legend has it that not even Stalin could pull down the 2015 European Tree of the Year.