Ancient ruins hidden underneath a modern luxury hotel.

Venice's island of the dead.

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

Over 50 exquisite hand-painted Renaissance maps decorate a Medici storage room.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

Crafted in 1911, this steam locomotive spent its entire working life in Flagstaff.

A Norwegian-born sculptor created these soaring guardian angels at the entrance to Hoover Dam.

This abandoned horse racing track was an exercise in hubris from its inception.

The world's only teal arches exist in a city that cares more about its aesthetic than an Instagram influencer.

When it was built in 1929, this historic bridge was the only place to cross the Colorado River for 600 miles.

The stone circle honors the 19 firemen who perished during the Yarnell Hill Fire.

A scrap-metal sculpture recalls an infamous 19th-century camel.

This huge dam across the Colorado River caused an armed standoff between two U.S. states.

This memorial pyramid marker honors one of the United States Government's first official camel riders.

This immigrant bridge once spanned the Thames but is now a fixture of an Arizona city.

Most-visited and most-photographed slot canyon in the American Southwest.

The arch that celebrated the completion of the Lincoln and Victory highways.

Experience a charming 1930s version of "infotainment."

An eatery for UFO seekers on the Extraterrestrial Highway.

A collection of haunted objects and macabre oddities under one roof.

Dyed by iron oxide over centuries, these sandstone rocks rise thousands of feet into the sky.

Art Deco stylings conceal the true nature of this bridge.

Thousands of turbines whir at the origin of North American wind power.

The world’s largest concentrated solar plant generates as many problems as megawatts.