This huge pile of volcanic boulders hides a stunning network of secret grottoes.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

An alchemist's "magic door" stands in the middle of a Roman park.

Gods clash with machines in a power plant regenerated as a museum.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

The yawning maw of this pagan visage is said to bite off the hands of liars.

The final resting place of the poets Shelley and Keats.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

This shining multicolored metro station deep under Naples is said to be the most beautiful in Europe.

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

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

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

The highway's southernmost spot is a beloved local attraction.

Climb a steep hill in 90 seconds on the second-oldest urban subway in the world.

This scented city oasis was a labor of love.

Hear the quietest sound from across the dome.

Colorful murals stationed throughout Charlotte bring poetry to everyone.

A faithful reproduction of Al-Jazari's enormous water clock.

On any given day this sprawling market houses literally tons of government-regulated gold, gems, and precious metals.

This indoor ski resort has a mountain contained inside a mall.

This mix of Islamic art, vintage vehicles, weaponry, architecture, and history is an ode to eclecticism. 

A replica of where the Last Supper was held.

A Christian-themed amusement park and complex rocked by scandals.