Hundreds of protractors affixed to surfaces all over the city.

A quiet, gothic haven nestled between Pittsburgh's Squirrel Hill and Point Breeze neighborhoods.

These disused steel furnaces are now haunting ruins that may one day be a national park.

Olfactory delights in San Francisco's Botanical Gardens.

Its buzzing collection honors vibrator history.

An artsy hidden staircase leads to breathtaking views of San Francisco.

This park contains a number of standing stones meant to heal and inspire.

A mine fire has been burning under the deserted town since 1962, but this church is still going strong.

The remains of a community that was forced to move for a dam that never materialized still rot in this Pennsylvania park.

The internal railway of one of the biggest steel plants in America has been transformed into a linear park with unique industrial views.

A train station that was abandoned by the coal industry and was later converted into a cocktail bar.

Buildings that dynamite couldn't bring down were abandoned because of bathroom issues.

Over 100 concrete munitions bunkers are all that remain of a Pennsylvanian village seized by the US government.

This eerily well-preserved coal town was saved from destruction by a Sean Connery movie.

This might just be the TARDIS of bookstores.

These beautiful ruins deep in the Pennsylvania woods are thought to have been a ski lodge or a speakeasy, but no one really knows.

Collection of trolley cars in the woods represent one man's attempt to preserve transportation history.

A modern ghost town whose inhabitants were driven away by the growth of nuclear power.

A stone arch leads to a cavernous 1930s spring house tucked away in the Pennsylvania woods.

Eccentric concrete mansion and museum designed and built by hand from the inside out.

"Dark Sky Park" is heaven on Earth for astronomers, one of the rare U.S. locations with no artificial light pollution.

An abandoned stretch of highway, deteriorating next to the operational one.

Mysterious rocks that ring musically when struck.

A toxic ghost town sitting atop a massive coal fire.