This railroad tunnel was once the longest in Massachusetts.

The macabre graffiti spectacle in a quarry in a Massachusetts forest reservation.

An alley way dedicated to graffiti and street art is a constantly changing street gallery.

From economic backbone of a community to deadly diving hole, these former stone quarries are now a park for rock climbers and graffiti artists.

Inspiring Herman Melville and Henry David Thoreau, Mount Greylock in western Massachusetts is the highest point in the state at 3,491 feet above sea level.

A historic bridge with a lovely acoustic anomaly.

This upscale streetwear store is hidden behind a fake Snapple machine in the back of a deli.

The glowing blue Nymphaeum of Emperor Tiberius.

Space program, pneumatics and more, bits and pieces, for movie sets or the common man.

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Abandoned railway line circling the city of Paris.

This former medical factory gives home to cutting edge arts in the shadow of a gas works.

A kaleidoscopic warehouse-maze of handmade neon signs.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

A student driver's nightmare.

A hands-off space for graffiti artists to hone and display their skills.

A strange egg in a mucky bog of western Ireland marks the spot of an aviation milestone.

You can see three Irish counties from this Neolithic hillside fort, once the seat of the Kingdom of Ailech.

Once the longest bridge in Ireland, this rusting span sits abandoned and overrun by nature.

The oldest pub in Ireland may also be the oldest surviving bar in the entire world.

An eccentric garden of sculptures crafted in India decorate an Irish green space dedicated to Alan Turing.

An eerie, derelict amusement park in Berlin.

This conical hill was built as a testing ground for an engineer known as the Glider King.