CA

Gilman Hall, built in 1916-1917, accommodated a growing College of Chemistry by providing expanded research and teaching facilities for faculty and students specializing in physical, inorganic and nuclear chemistry. Work performed at Gilman Hall helped advance the fields of chemical thermodynamics and molecular structure, and has resulted in multiple Nobel Prizes. The Hall is most famous for the work of Glenn T. Seaborg and his coworkers, which included the successful identification and production the element Plutonium. Seaborg received the Nobel Prize in 1951 for his accomplishments.

The Fresno scraper established the basis for the modern earthmoving scraper, being able to scrape and move a load of soil, then discharge it at a controlled depth. It quadrupled the productivity of manual labor, replacing hand shoveling of earth into horse carts.

The historic Folsom Power House #1 marks one of the first successful uses of hydroelectric power in the world and the first successful transmission of power long distance (twenty-two miles to Sacramento). The old Folsom Power House still shelters the machinery generated to drive streetcars and illuminate the city of Sacramento.

Established in 1929, and owned by several different aviation companies through its history, the Downey site was the design, test, and production site for various airplanes and spacecraft that defined American aerospace accomplishments in the 20th century.

Stretching 242 miles from the Colorado River on the California-Arizona border to its final holding reservoir near Riverside, California, the Colorado River Aqueduct consists of more than 90 miles of tunnels, nearly 55 miles of cut-and-cover conduit, almost 30 miles of siphons, and five pumping stations. Supplying approximately 1.2 million acre-feet of water a year - more than a billion gallons a day - it helped make possible the phenomenal growth of Los Angeles, San Diego, and surrounding Southern California areas in the second half of the 20th century. 

A product of the Northern California Gold Rush, the Bridgeport Covered Bridge is believed to be the longest, single-span, wooden covered bridge in the United States. Crossing the south fork of the Yuba River at a span of 233 feet, the bridge was built by the Virginia City Turnpike Company as part of a 14-mile toll road authorized by the California state legislature. The toll road was an essential link connecting Virginia City, Nevada, and the silver-producing Comstock Lode with the centers of California commerce.

All building materials were made fire-resistant to protect against incendiary bombing. Treatment involved a vacuum process of salt impregnation. During construction, high winds caused a partial collapse of some members. The ruined materials were piled for incineration, but would not burn; so the rubble was buried on site. Years later, a farmer leasing ground on the site plowed up some of the materials. They were reported to still be in good condition.