The former Nazi Germany concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

The unsettling remnants of a torn down movie set lies nearby the ruined location of the actual Płaszów Labor Camp.

This Polish cave has housed a dragon, a brothel, and an enduring legend.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

Real bones which are said to have belonged to a Polish dragon.

The world's oldest bookshop still in operation.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

Located in the thermoelectric factory that once powered the entire city, this Portuguese museum is shockingly fascinating.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

This small chapel is built of human bones and decorated with a golden skeleton.

Perhaps the most spectacular grotto along the Algarve coastline.

Have a seat with the father of modern computing at this Manchester monument.

One of the world's largest collections of pharmaceutical artifacts.

This work of engineering is imbued with elegance and ingeniousness.

If James Bond bungee-jumped off the side of a 720-foot dam, would you do it too?

This medieval footbridge in the Swiss Alps is known to attract cliff-jumping daredevils.

The world's longest and deepest train tunnel.

This historic covered bridge contains a series of macabre paintings that communicate one thing: everyone dies.

This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.

The alpine falls where Sherlock Holmes apparently met his demise can actually be visited.