Half of a waterfall goes into the river while the other half seems to disappear.

This large midwestern cavern features impressive rock formations and an underground waterfall.

This lab's maddening silence is good for business but bad for sanity.

A wonderland of caves in eastern Iowa.

An underground wonderland in Iowa.

Most comprehensive museum in America devoted to one ethnic group.

An unlikely Transcendental Meditation haven in the American Heartland built around the ancient Vedic principles of balance and harmony.

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

This enchanting forest trail leads to ethereal abodes and a giant bird's nest.

The only surviving prototype for Buckminster Fuller's house of the future.

Strange physical sensations and optical contradictions keep visitors coming back for more.

Once an ambitious nature spa, these forest ruins now provide a serene monument to failure.

A futuristic climate change study is nestled deep within this public land.

Journey through the largest remaining peat bogs in the contiguous United States to see the wilderness as it once was.

A museum dedicated to the exploring past, present, and future innovations.

Funhouse of found art and participatory sculpture.

20,000 pieces in a Frank Gehry-designed building.

A museum within a museum, devoted to history's most questionable medical devices.

The history of funerals and funerary customs.

Moving, mind-blowing metal sculpture work of an outsider artist.

A Museum of Holography frozen in 1974.

A collection of art crafted from various hardware tools.

This lush 12-acre site was once named the finest Japanese garden in North America.

A former atom smasher turned into an art gallery.