These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

Although it appears ancient and mysterious, the quirky folly was actually built 200 years ago by an eccentric estate owner.

A dramatic sculpture high up in Yorkshire with vistas on an industrial scale.

Britain's tallest megalith towers over the cemetery of a quiet English village.

Now an entertainment complex, the Lingotto building was once an avant-garde auto factory with a test track on the roof.

Da Vinci's equestrian statue, 500 years in the making.

The odd depiction of the Virgin Mary and baby Jesus is rooted in the Catholic Church's eradication of Catharism.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

A sulfuric hellscape in southern Italy.

Europe’s oldest natural human mummy.

Tourists to the mountaintop Sicilian town often overlook its ancient fortifications.

In pastoral England, a plaque marks where an imaginary community addressed the problem of combat mortality.

In an isolated field near a dilapidated barn stands this chilling portrayal of the plight of the Nuba peoples of Sudan.

Model Trains and Much More in Hamburg.

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

A wunderkammer of exoticism immortalized by Tom Waits.

A modernist landscape of water and sci-fi concrete.

A mythical chimera first sculpted in 1936 as a mix of the main animals of Texas livestock.

A trio of colossal statues spread across a Dallas neighborhood chart the emergence of a giant robot born of a locomotive and spilled gin.

This collection of bronze hands comes from astronauts, presidents, baseball greats, and more.

A "Texanic" (gigantic Texas) collection of Art Deco architecture at Dallas' historic Fair Park.

A copy of the brutal decapitation device that predated the French Guillotine by about 200 years.

The names Lúthien and Beren can be found inscribed on the shared grave of the famous writer and his beloved wife and muse.

The centuries-old obelisk may have inspired J. R. R. Tolkien.