This hydrochronometer was invented by a Dominican monk and is a prime feature in this garden.

This ancient market is often referred to as the oldest shopping mall in the world.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

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

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

A forgotten "city of water" underneath the famous Trevi district.

2300-year-old Roman road connecting the empire.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

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

This oversized flute-playing Ancestral Puebloan deity is also a landmark of Southwestern kitsch.

Dine like an American revolutionary at Colonial Williamsburg.

A 90-year-old underground water reservoir offers a more industrial kind of tranquility.

Semaphore saints, a golden dragon's head, and a stone carved with religious warnings all call this cathedral home.

This sculpture marks the spot where one of the greatest Roman rulers was proclaimed emperor.

This spectacular track has run continuously since 1882.

For over a century, it has been a tradition to raise a flag at the top of this 450-foot sandstone pillar on the 4th of July.

Dramatic river bend surrounds a natural red-rocked pedestal.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

The fading, forgotten remains of a once bright and booming factory.

This memorial includes fragments from one of the greatest tragedies in United States history.

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

Red sandstone structures dominate this landscape, which has been inhabited for some 5,000 years.

This sinkhole in the Arizona desert is filled with carbonated, arsenic-rich water

The largest underground pedestrian tunnel system in the U.S. mostly caters to the people working in the offices above, but provides a great, air-conditioned way to traverse the city.