A giant, Gilded Age mansion that once belonged to the beer baron of Milwaukee.

A unique botanical garden housed in three giant geodesic domes.

Originally conceived as part of a proposed Arizona State Capitol building in the 1950s, this structure built in 2004 stands as a monument to the architect's legacy.

The final resting place of the businessman-turned-astronomer who helped discover Pluto stands near his observatory.

Red sandstone structures dominate this landscape, which has been inhabited for some 5,000 years.

An incredible airplane graveyard sits outside this small museum dedicated to preserving aviation history.

The biggest solar telescope in the world helps reveal the secrets of our sun.

A small canyon with petroglyphs and a seasonal waterfall, only a short hike from the remnants of old Route 66.

A self-built castle made by a mysterious man.

The eclectic home of a leading Turkish architect is a gorgeous piece of eye candy.

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

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

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

A meow-velous tribute to a beloved street cat, made famous on the internet.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

A marvel of Byzantine engineering under the streets of Istanbul.

This arch granting triumphal entrance into Antalya was designed to honor the emperor's visit.

Once described as the "Eagle's Nest," this ruined ancient city rests on a remote mountaintop.

Naturally protected city carved from a rock face.

This ancient subterranean megalopolis is known for the hot oil traps that were installed above each of its entrances.

Live a night as a Byzantine King, with a minibar and private jacuzzi.

While not Turkey's deepest underground city, this subterranean redoubt is the largest.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

A tour de force of a fountain, memorializing a man who loved fountains more than anything else.