A volcanic fissure over two miles long and up to 70 feet deep.

This ultra-modern California span is actually a titanic solar clock in disguise built by famed architect Santiago Calatrava.

Massive crater in central Oregon.

This large maar crater in Oregon is the bigger brother to Hole in the Ground.

Two mammoth statues inspired by equally tall tales lure tourists to this roadside attraction.

This historic steamboat is scuttled just a few hundred feet from where it was built over a hundred years ago.

A collection of colorful dinosaurs hidden in an actual rainforest.

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

Each winter this underground cave forms a dazzling ice palace.

This natural marble cave is one of only five national monuments in Oregon.

A tourist attraction founded around a slumping cabin.