A symbol of friendship between the mountainous regions of Switzerland and Bhutan.

Medieval irrigation channels built into the sides of mountains provided Valais with water for hundreds of years.

The largest underground lake in Europe.

Enormous, fluffy dogs frolic around this museum dedicated to a legendary Saint Bernard.

Artworks by loners, prisoners and the criminally insane.

A tiny rural community in Switzerland was home to one of history's most shocking murders, and led to the banning of Absinthe for nearly a century.

Over 3km of caverns and caves at the Switzerland-France border contain the largest underground river in Central Europe.

Underwater roads undetectable from the surface used for escape routes from foreign invaders.

This former KGB building is now a museum memorializing the people who suffered during the Soviet regime.

A century-old prison in the heart of Vilnius is now a lively bar, dance club, and artist residency.

Over time, this castle grew to encompass the entire island.

Once known throughout Europe, this tiny and unusually progressive 18th century micro-nation within Lithuania now lies in ruins.

Ever-growing collection of devils in art.

An old hill fort covered in over 100,000 crosses is a symbol of Lithuanian nationalism and beliefs.

Lithuania's outdoor sculpture trail of wooden folk art.

A narrow strip of land is home to the tallest migrating dunes in Europe.

Sculpture garden of religious statues made it through Soviet rule.

One of the best-preserved wooden manor houses in Latvia, decorated with painted interior walls.

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

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

These abandoned vessels are destined to be reclaimed by the forest.

The widest waterfall in Europe is a natural wonder and one of the only places where fish are caught in the air.

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

Ancient rock-hewn town that witnessed key events of Georgian history.