Stalactites and stalagmites in a beautifully lit cave.

Drink the 'Blood of Christ' in this Roman Catholic fever dream.

A 16th-century Andalusian palace.

The world's largest wooden structure.

The home-turned-museum of Barış Manço, the mustachioed Turkish Elvis for children.

A gorgeous, Gaudí-esque stairway constructed in the city of Istanbul by a prominent Jewish family.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

A marvel of Byzantine engineering under the streets of Istanbul.

This striking memorial is one of Estonia’s most controversial Soviet leftovers.

Relics from an era long gone, sit idle outside this Estonian museum.

A random tree outside a Budapest hotel has become a DIY shrine to the late singer.

A museum in the childhood house of a medical pioneer.

Museum dedicated to the terror regimes of Hungary.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

This ruined 15th-century hermitage is steeped in myth and mystery.

The world's largest collection of witchcraft regalia.

Stonehenge has nothing on Castlerigg’s views.

As can be expected from a centuries-old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

Venice's "Island of the Mad."

This tangled English forest looks like something right out of a fairytale.

A circle stone within a stone circle.

A unique waterfall that some believe attracts the fairfolk.