Colorado

Now a national historic site, this mill operated from 1913 to 1943, processing ore brought via the 22,000 foot Argo Tunnel. At the time it was built, it was the largest mill of its type in the world. It is now a tourist attraction.

A three-story, hand made, medieval-style castle under construction since 1969. The castle is being built entirely by one man, Jim Bishop, who calls his structure "a poor man's Disneyland." It is built primarily of native stone gathered from the surrounding...

A group of several prisons including ADX-Florence, a state-of-the art $223 million federal "Supermax" prison, which is known as "the Alcatraz of the Rockies." It's perhaps the flashiest (certainly the most controversial) of the nine-state and four...

Underground command center for monitoring the skies and space for hostile incoming weapons. Cheyenne Mountain was built with the knowledge that it would be a primary target for a nuclear attack, and it is perhaps the most fortified large underground...

This museum houses more than 50,000 rare old photographs, papers and artifacts relating to Colorado railroads. Outside, displayed on 15 acres, is a collection of over 100 narrow and standard gauge locomotives.

America's longest and highest narrow gauge steam railroad, runs between Chama, New Mexico, and Antonito, Colorado, a distance of 64 miles through mountainous terrain, with elevations as high as 10,015 feet at Cumbres Pass, Colorado. Built in 1880 with the...

Denver's much maligned $4.8 billion airport, opened in 1995. It was one of the largest civil works projects in American history. It covers 53 square miles, making it the largest airport in the United States by land area. Currently there are four separate...

Drop City was a community that formed in the hills of southern Colorado in 1965, which went on to become a sort of icon of the rural 1960s communal living that seemed to be blooming at that time. Singled out by the media as exemplary, Drop City was known for...

This disposal cell, near Bodo Canyon, in the hills above the town of Durango, Colorado, was built by the DOE to contain 2.5 million cubic yards of radioactive tailings and buildings from the days of uranium processing at a mill in town. The mill operated (...

The Durango Uranium Mill was one of two uranium recovery plants in Colorado set up secretly in 1943 to produce uranium for the Manhattan Project. Uranium from this site, and the other in Uravan, was shipped to the new secret refinery in Grand Junction, now...

Designed by Herbert Bayer in 1954, making it in all likelihood the first "earthwork" done within the context of contemporary art; the piece is maintained and visible at the Aspen Institute's Aspen Meadows campus in Aspen, Colorado. Down a nearby path is...

A cluster of a six state prisons in Canon City, which includes the Four Mile Correctional Facility, and the Fremont Correctional Facility. These, along with the Florence Corrections Complex, a cluster of four federal prisons, including a notorious "supermax"...

Located at 11,153 feet in elevation, the Eisenhower Tunnel is the highest vehicular tunnel in the nation's interstate system, and probably the highest in the world. Built in the 1970's, the 1.7-mile-long tunnel has two bores, one for eastbound (known as the...

A group of three federal prisons including the Supermax, a state-of-the art $223 million Federal Prison, which is known as "the Alcatraz of the Rockies." It's perhaps the flashiest of the nine-state and four federal prisons located in Fremont County, Colorado...

A large mechanized infantry base, with 137,000 acres and around 25,000 active duty personnel. Additional maneuver activities take place on the 235,000-acre Pinon Maneuver Site, 100 miles southeast, acquired in the 1980s. Infantry divisions based here have...

Monument at the intersection of Arizona, New Mexico, Utah, and Colorado.

This was the site of a former uranium mill, which was removed and cleaned up beginning in the mid-1980s, as part of the federal Uranium Mill Tailings Remedial Act Project. Also known as the Climax Mill site, it covers approximately 114 acres. The mill...

A radioactive waste disposal site for material from a former uranium mill, removed as part of the federal Uranium Mill Tailings Remedial Action Project. The Climax Mill, located on the Colorado River in the middle of Grand Junction, operated from 1950 to 1970...

This Department of Energy (DOE) uranium mill and laboratory was originally founded as a source of uranium for the Manhattan Project. It later became the center of the government-initiated uranium mining boom of the 1940s and 1950s, propelled by the defense...

A 29-acre disposal cell created by the DOE in 1995 to contain the contaminated tailings and mill buildings from a uranium mill in Gunnison, Colorado, six miles away, which was cleaned up as part of the federal Uranium Mill Tailings Remedial Action Project....

Former 61.5-acre uranium mill site, active from 1958 until 1962. As part of the subsequent clean-up process, around 39 acres worth of radioactive mill tailings had to be removed, a process which took from 1992 to 1995 to complete. This undertaking was...

A diamond mine at 8,000 feet in the Rocky Mountains near the Wyoming border. Went into full operation in June 1996, then went bankrupt in 2000. One of only four diamond mines in the country, which together make up less than 1/100th of one percent of the world...

The Leadville mines were a major producer of lead, zinc, silver, copper, and gold ores. It is a historic mining district, with many underground mines. At 10, 200 feet, Leadville is considered the highest incorporated city in...

The main site for Lockheed Martin's Space Systems Company is a 5,400-acre industrial site, with numerous production, test, and space simulation facilities, and over 70 laboratories.  Lockheed Martin's Space Systems Company designs and...

Lowry is a closed Air Force Base in suburban Denver that is being redeveloped into a network of businesses, schools, and new urbanist housing developments. The base was closed by BRAC in 1994, and buildings began being demolished in 1996. Lowry started out in...

A complex of museums and exhibits located next to a rural RV park, featuring displays of over 7,000 different species of invertebrates, giant beetles, moths, butterflies, spiders, scorpions, and artifacts from - but not limited to -  tropical areas of...

There are two disposal cells at the former uranium mining and processing center near the town of Maybell, in the northwestern corner of Colorado. The east cell is the repository for wastes from the uranium mine and mill that operated here from 1955 to 1964,...

One of the highest observatories in the world, at a height of 14,100 feet. Operated by the University of Denver, the 2100-square foot observatory complex was completed in 1996 and has twin 28-inch telescopes that can be operated remotely.

A 6.2-mile railway tunnel through the Continental Divide in the Rocky Mountains, completed in 1928. One of the longest mainline railway tunnels in the USA.

Operated by the Department of Energy, this multiple laboratory facility is engaged in research and development in renewable energy and related technologies. Some of the facilities include: the Solar Energy Research Facility (SERF), which houses 42...