Monasteries on rock pillars, once accessible only by frayed ropes.

The ruins of this monumental city founded by the first Roman Emperor are strangely overlooked by most travelers.

Ancient Greek oracle of the dead.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

Legend says this sacred tree was a gift from goddess Athena.

These caves secretly held national treasures during World War II.

A Bronze age settlement on the Greek island of Santorini might have been the inspiration for Plato's Atlantis.

The innocent intentions of this monument are somewhat lost in the sculpture's muscled imagery.

There’s a hidden military meme engraved on the World War II Memorial.

The only tennis court that falls under the jurisdiction of the central bank.

A much-maligned monument to teetotalism.

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

A computer bug so primitive it was an actual insect.

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

Look closely and you’ll notice that the color changes a third of the way up the tower.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”