This now abandoned restaurant provides some of the most amazing views of Lisboa.

A 19th-century mansion houses the largest collection of gin in the European Union.

The walls of this small village have been turned into a living street art gallery.

Houses are tucked between, on, and underneath giant boulders.

A small Portuguese cottage formed between boulders in the countryside.

This gaping hole in the middle of a remote mountain lake looks like a portal to another dimension.

Hidden beneath the streets of London is a secret subway that only carried mail.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

The history of radiation is on safe display at the foot of a radiation science laboratory.

This massive library holds what was once the largest book collection in the world.

The oldest stone house in Paris was built by its most famous alchemist.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

The secret cells in the basement of the KGB's Estonian "Grey House" have been preserved as a grim Cold War museum.

This secret Swiss fortress is disguised as a harmless pink house, complete with fake windows.

This natural French spring has been turned into a magical grotto by Roman and medieval constructions.

The site of a concentration camp where inmates were made to take part in one of the largest counterfeiting operations in history is now hauntingly empty.

A calico cat named Tama was the wildly popular Super Station Master at this train stop in southeast Japan.

After a profound show of devotion for his master, a dog becomes the symbol of loyalty for an entire nation.

This spacecraft-shaped water tower is only a part of the mysterious UFO mania in this Brazilian town.

A memorial to a Swedish hockey player's "encounter" with aliens.

Humble beginnings for one of the world's most famous scientists.

A South African bar inside a hollowed out 6,000-year-old Baobab.

The superstar of Cold War nuclear bunkers has been featured in countless films but is now barely operational.