Tour the luxe "glass cage" that inspired and unnerved the architecture world upon its debut.

Chilly air billows out from the entrance of an abandoned mine on a steep hillside, providing a refuge for Ice Age fauna and flora.

The oldest university museum west of the Mississippi retains its 19th century feel.

Piled high inside this warehouse and coffee shop are salvaged goods that span every corner of the globe.

The magazine keeps a perfectly groomed display garden for its photo shoots.

The remains of a bustling turn-of-the-century park built to showcase the wonders of electricity.

Millions of dollars worth of sculpture decorate this Iowa city center.

An old town theater converted into a celebration of the hobo legacy.

The world's only three-story rotary jail is now a museum to a bizarre trend in prison design.

A four story, football field-sized, nine-grotto creation made of shells, minerals, and rare stones.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

A warning to the weak-kneed: This narrow bridge does its swinging eight stories high.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

A waterfall 600 ft. inside a mountain, once the bane of gold miners, is now a spectacle of nature.

A fascinating collection of art made from petrified wood and fossils by two octogenarian twin brothers.