These precariously placed ruins harken back to a 13th-century castle.

Rare recess caves fill this unbelievably beautiful Ohio park.

Faces carved into the cliffs create an otherworldly walking trail.

A throwback train ride transports passengers through one of the lesser-known national parks in the country.

An elegant sandstone stairway built by the WPA still connects two neighborhoods in Akron.

The shattered remnants of a meteor that struck Santa Fe more than a billion years ago.

A relief that wraps around the concourse of Los Angeles's World Trade Center marks one of the city's failed urban design plans.

The maze-like transportation hub contains abandoned areas, derelict stores, and a resident bat colony.

An ingenious solution to a tricky engineering problem, this spiraling bridge takes drivers for a dizzying spin.

The highest pedestrian bridge in Singapore looks like a series of undulating waves rising between two public parks.