A decaying, yet still functioning, work of communist architecture.

Windswept juniper trees resemble surrealistic artwork, however, this juniper is actually a work of art.

Hidden in this modern shopping center is a relic of 16th-century capital punishment.

A small museum dedicated to taking the taboo out of all things related to poo.

This fantastic museum honors Gloucester waterway heritage.

This historic furnace was once used to produce cannonballs during the Civil War.

A double cantilever system bridge that was designed to prevent flood damage.

This Roman theater was crafted into the local tuff rock and was rediscovered during the 19th-century.

Around 160 years ago, this spot marked the location of a wharf along the shores of the Charles River.

The only geyser in the state of Pennsylvania is caused by pressure from an abandoned coal mine outside of the ghost town Centralia.

This public elevator links the lower city to the upper city of Salvador.

The industrial monstrosity known as Bagger 258 is a colossal mining machine built in the DDR - but now left for dead in a German field.

This water tower has been a staple of the Rochester skyline since 1931.

This edgy museum will whet your appetite for the industrial history of Western New York.

The 2,000-year-old beam is tucked within the pedestrian entrance to the old London Bridge.

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

This pump on the bad side of Victorian London betrayed a horrifying revelation about the water supply.

The fierce beast perches atop a pedestal marking where the historic City of London gates once stood.

A Roman spa buried deep beneath the City of London.

The first tunnel to be dug beneath a river, repurposed as an art and museum space.

Public access to clean drinking water was an instant hit among the masses.

In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.

Catacombs turned marketplace.

Wedged between two buildings at the Great Ormond Street Hospital is this secret music installation.