Standing atop 2nd-century Roman ruins, this church is one of the oldest and most iconic in Old Cairo.

The medieval center of the Islamic world was also once the seat of Saladin's sultanate.

Ancient serpentine sacrifice holder that has stood the test of time.

Legend says if you stick your thumb in the hole and it gets wet your wish will be granted.

A marvel of Byzantine engineering under the streets of Istanbul.

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

The world's first and only three-segment bascule bridge folds up into the shape of a capital "N" to let boat traffic through.

This monument to those fallen in the World Wars is accompanied by a U-boat that Germany bought for a Deutsche Mark.

Visitors dating back to the 1600s carved their marks in the stones of the iconic tower.

Explore this medieval cathedral by trying to spot all the malevolent monsters hiding in its beautifully colored windows.

The "Prussian Versailles" that is as glorious today as when it was built.

Every hour the doors open to reenact the legend of the heroic mayor who saved his town by drinking a gallon of wine.

This incredible stone temple is a monument to death, victory, and fantasy architecture.

A small but immensely extravagant palace built by the "Night King."

This medieval cathedral houses stained-glass windows featuring saints and pretzels.

This Late Gothic building that once housed Erasmus is now known as the filming location of "Suspiria."

These paved rills bring freshwater into Altstadt and could spell wedding bells for whoever stumbles into the waters.

A stonemason's hilarious revenge came in the form of this peculiarly positioned gargoyle.

This historic stone bridge has an entire neighborhood clinging to its sides.

The fairy tale castle of the "fairy-tale king."

Fantastic views and thousands of love locks.

The sweet story of how American cargo planes became known as "Candy Bombers" during the Berlin Blockade.

Carved fountains poignantly placed in parks and in front of special monuments.

After years of being casually peed on by humans, this tree is peeing back.