This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

A fortified city, home to a remaining population of five families

One of the most spectacular canyons in the world.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

This ancient Spanish castle sits high upon a hilltop.

1513 Turkish world map, full of European state secrets and snarky commentary.

Famed architect Antoni Gaudi built this generous thank you gift to a friendly host who housed him during a job.

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

A marvel of Byzantine engineering under the streets of Istanbul.

Museum dedicated to the sacred leaf of the Andes.

Popular tourist destination where witches in dark hats sell dried llama fetuses for good luck.

At Monet's beloved home you can still see the Japanese bridge, waterlilies, and weeping willows that were the subjects of some of his most iconic paintings.

The massive cave church of Cairo's Zabbaleen community is one of the largest Christian churches in the Middle East.

The once great capital of Egypt now crumbles forward as evocative ruins.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Thousands of exquisitely carved stone water storage wells, hundreds of stone steps fill this exquisite medieval stepwell.

More than half of this Indian palace is drowned but it looks all the more spectacular for it.

Everything from a plane to your own two feet are needed to reach this jungle resort.

One of the largest Buddhist stupas in the world keeps an eye out in every direction.

Sacred Buddhist home of some spiritual monkeys.

These Nubian pyramids are strange and unique, even by pyramid standards.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.