An improbable water gap where the West Walker River, paralleled by a state highway, crosses the Singatse Range between Smith and Mason Valleys.

This magnificent natural sandstone bridge is one of the largest in the world and is an iconic symbol for Lake Powell.

Beehive charcoal kilns and slag deposits mark this late 19th century camp centered on a smelter.

An iron monument on the 120th meridian as surveyed, one of only four marking the boundary between Nevada and California north of Lake Tahoe.

A Native American petroglyph, the site of an emigrants' waystation, and the ruins of an early 20th-century sheep camp are all found at this crossroads.

Once owned by the largest employer in Colorado, these ovens have been abandoned for over a century.

Site of a tragedy on the Oregon Trail.

This extraordinary model train layout covers over 1,700 square feet, with multiple trains running simultaneously.

A comprehensive collection of toy and model trains, largely from the mid-20th century.

A field of nothing but boulders which resembles a giant's gravel driveway.

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

Metal monsters made from repurposed materials lurk alongside this Pennsylvania road.

This jail which was in service for over a century is now open for curious visitors.

An enormous boulder deposited by the Scabland floods lies in the Quincy Basin among a host of smaller boulders.

A narrow fjord-like lake, the third-deepest in the United States, runs for over 50 miles into the Cascades of Washington state.

The "Grand Canyon of Southwestern Idaho" makes a spectacular gash across the flat Snake River plain.

The only undammed section of the Columbia River in the United States has been preserved, ironically, by its proximity to the Hanford Nuclear Reservation.

In the high desert east of Bend, the University of Oregon maintains a research observatory on a remote mountain peak.

One of the northernmost occurrences of western juniper can be found in the sand dunes of Washington's Palouse.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

The second-largest giant sequoia in the world.

A haven for wildlife amid the farmlands and development of the Willamette River Valley.

Named for a prominent scout and explorer, this Wyoming state park encompasses a replica of an 1840s trading post, a 19th-century Army outpost, and early 20th-century automobile lodgings.

A large wind turbine installation in central Washington State is home to an extensive set of interpretive exhibits.