The tech giant built three enormous glass orbs in Seattle so employees could work inside a rainforest greenhouse.

Walk the whole Mississippi River!

This ancient octopus-like tree was saved from destruction thanks to shady reporting.

America's only nuclear missile silo open to the public.

A recreated Stonehenge stands in a country field, complete with Easter Island moai heads standing as sentries.

Only known mainland rookery of the threatened Stellar sea lion.

Friction between grains of sand cause a curious "singing" sound.

Treehouse motel and treehouse-building school.

One of the largest, oldest, darkest, quietest motel rooms in the world.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

The lowest point in North America is home to an undrinkable pool surrounded by fields of geometric salt flats.

These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.

This naturally heated mountainous creek has created a group of neon blue pools of potentially deadly boiling water.

San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

These towering spires and glowing walls are carefully crafted from hundreds of thousands of icicles.

Constant erosion has created a surreal landscape of bleached and preserved fallen trees.

A well-preserved Ancestral Puebloan ruin tucked beneath a desert cliff.

This massive redwood tree has a hole in the base big enough to drive through.

Faces carved into the cliffs create an otherworldly walking trail.

The largest permanent Monopoly board makes one of the longest games even bigger.

This historic national park is covered in the stunning ruins of red rock pueblos.

A multi-storied adobe complex has been inhabited for more than a thousand years.

This permanent exhibition celebrates the finest of our heartless automatons both real and fictional.

Witnessing the might of this dessert-colored desert waterfall is a rare, powerful treat.