Over several decades, one of London’s most iconic city gates was dismantled, moved out of the city, and then moved back.

French sculptor Paul Moreau-Vauthier transformed the site of a 19th-century massacre into a haunting memorial.

This ancient Roman town was revered for the healing waters of its sacred spring.

This monument is dedicated to Balto, the heroic Alaskan sled dog.

This 400-year-old tree is actually an immigrant from North America.

An ancient Roman relief beautifully preserved on the façade of a house.

A unique collection of figures perform down the facade of the Gene Frankel Theatre.

London’s first road overpass is so old that it was originally built for horse-drawn carriages.

The niches over the western entrance of Westminster Abbey honor individuals from the 20th century who gave their lives for their Christian beliefs.

A modern-day Lascaux cave underneath Paris.

Abandoned railway line circling the city of Paris.

Love is in the air along the small street in Brooklyn.

The San Marino-Rimini railroad was short-lived but this tunnel once provided shelter for hundreds of refugees during World War II.

The largest living museum in the Northeast recreates life from the Early Republic period complete with costumed historians and reenactors.

The unique design of these skyscrapers in a Paris suburb led to them being nicknamed "cloud towers."

A suburban housing complex with astonishing architectural features, locally nicknamed "the Camemberts."

After traveling the world, one of the last remaining fully-rigged three masted iron-hulled cargo ship in the world found its home in New York.

This tower is one of the best-preserved (and least-visited) remnants of medieval Paris.

One of London's lost rivers runs through a pipe over the tracks of this subway station.

An interim housing alternative to FEMA trailers that is designed for densely populated areas during recovery and rebuilding following a natural disaster.

This statue of one of the engineers who created the London Underground hides a ventilation shaft for the tube lines that run under the street.

The French leader's hat sits in a glass case at the oldest restaurant in Paris.

The bones of the Biblical Magi traveled to Constantinople and Milan before landing in their current home inside an elaborate golden reliquary in the Cologne Cathedral.

The site where two doves fell in love.