The Palomino Valley Off-Range Holding Facility, destination of wild horses removed from public lands, is about 20 miles north of Sparks on the east side of Highway 445.
The valley, which extends to the southeast, was the site of a rocket engine testing facility owned by the Rocketdyne division of North American Aviation in the 1960s, according to a document provided by the Palomino Valley General Improvement District.
The BLM corrals, not there at the time, are at the intersection of Ironwood Road and Pyramid Highway (445) in the following map. Ironwood Road may have been moved slightly to the south to eliminate the jog and accommodate a larger holding facility.
The Nevada Field Laboratory, as it was called, was decommissioned in 1970. Engines for the Gemini and Apollo spacecrafts, tested there, eventually put Neil Armstrong and Buzz Aldrin on the moon in 1969 and returned them safely to earth.
A 2014 report by USA Today describes the facility, as well as some of the environmental issues that were found as the area transitioned to a housing development.
A few artifacts remain. The exhaust tubes, mentioned in the story, are still there. They were built in Area B of the map above. Today, the land is owned by Boeing.
Plans for the Valley, post-Rocketdyne, never fully materialized. Most of the roads are not paved but many of the parcels are 40 acres in size or larger.
Two years ago, a roundup in the area resulted in controversy when privately owned horses were captured and never returned.
UPDATE: More photos of the Rocketdyne facility can be found in this online gallery by the Reno Gazette Journal.