One of the largest free-standing structures ever built, this dirigible hangar is now simply a giant skeleton.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

Elvis's own personal tropical hideaway.

This two-room shotgun shack in Tupelo is the birthplace of a King.

This twice-relocated "Usonian" home is among the smallest built by master architect Frank Lloyd Wright.

Deep in the Negev Desert, the world's tallest solar tower looks like a sight straight out of science fiction.

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

A building so large that it has its own weather.

A tunnel with windows, so you don't miss out on the impressive views.

A mysterious monument meant to be a guide into "an Age of Reason" was destroyed after an apparent bombing.

The only surviving fragment of the lost Narragansett Pier Casino.

The world-record holder for the longest bridge stretching continuously over water.

The mortal remains of an estimated 70,000 people lie in the basement of a monastery in Lima, Peru.

This 29-ton granite ball spins around at the slightest touch thanks to a scientific phenomenon.

An oddities shop that dabbles in the deathly and beautiful.

Tour the world's largest deep-hole dimension granite quarry, where you can view the plant where gravestones are made and roll a ball down the outdoor granite bowling alley.

An earthwork sculpture built by Robert Smithson in the Great Salt Lake only reemerges during drought.

This 1,700-pound edible sculpture is way better than your average chocolate mousse.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

The only place for a truly presidential dram.

The medieval network of canals hidden underneath the city is opened to explorers each year.

This geometric feat is a testament to the Incas' mesmerizing architectural abilities.

This massive swimming pool is the high tech home to the human-powered submarine races.

There has been an astronomical clock on this spot since the 14th century.