Air Force Academy (Colorado Springs) — free visitor center and tour stops
Dragonmans Military Museum (Colorado Springs) — personal collection of a guy with an obsession for collecting
Fort Garland Museum (Fort Garland) — army fort from 1800s, probably not worth a special trip, but interesting if you’re in the area
National Museum of World War II Aviation (Colorado Springs) — restored planes and exhibits on aviation during the war
Peterson Air and Space Museum (Colorado Springs)
Pueblo Weisbrod Aircraft Museum (Pueblo)
Wings over the Rockies Air and Space Museum (Denver) — decent volunteer-run museum with several aircraft on display
Mining and Industry
Argo Mill & Tunnel (Idaho Springs) — tour of a gold mine
Colorado School of Mines Geology Museum (Golden) — more geology than history, with many interesting gems and minerals
Georgetown Loop Railroad (Georgetown) — Steam engine ride on old narrow-gauge tracks through a mountain pass.
Mollie Kathleen Gold Mine Tour (Cripple Creek) — Interesting tour of a mine 1,000 feet below ground level.
Steelworks Center of the West (Pueblo) — small museum about the local steel industry
Vindicator Valley Trail (Goldfield) — trail past ruins of several gold mines
Western Museum of Mining and Industry (Colorado Springs) — exhibits on mining in the American West with a lot of working machinery
Money Museum (Colorado Springs) — exhibits on the history of money and samples of U.S. gold coins.
United States Mint (Denver) — free tours on weekdays
McAllister House Museum (Colorado Springs) — first permanent house in Colorado Springs.
Miramont Castle (Manitou Springs) — tours of an old mansion
Molly Brown House Museum (Denver) — home of millionaire activist and Titanic survivor Margaret Brown
Colorado Railroad Museum (Golden) — decent size collection of railroad equipment and a model train layout
Cripple Creek & Victor Narrow-Gauge Railroad (Cripple Creek) — short trip behind an old steam engine past old gold mines
Cussler Museum (Arvada) — antique cars from Clive Cussler’s private collection
Dougherty Museum (Longmont) — interesting collection of antique vehicles and farm machinery
Dr. Lester L. Williams Fire Museum (Colorado Springs) — museum of fire fighting in Colorado Springs
Forney Museum of Transportation (Denver) — interesting collection of cars, train cars, bicycles, and motorcycles.
Penrose Heritage Museum at the Broadmoor (Colorado Springs) — carriages and an exhibit on the Pikes Peak Hill Climb race
Pikes Peak Historical Street Railway Foundation (Colorado Springs) — history and restoration of trolleys and train cars
Bent’s Old Fort National Historic Site (La Junta) — old trading post on the Santa Fe Trail
Buffalo Bill Grave and Museum (Golden) — small but interesting museum
Colorado Springs Pioneers Museum (Colorado Springs) — local history and a 1903 elevator that you can operate
Cripple Creek District Museum (Cripple Creek) — history of Cripple Creek, the railroads, and the gold mines
Cripple Creek Heritage Center (Cripple Creek) — free museum with displays on local history
Cripple Creek Jail Museum (Cripple Creek) — jail building in use for 90 years
El Pueblo History Museum (Pueblo) — tiny museum with a one-sided perspective of history
Fort Vasquez (Platteville) — rebuilt adobe walls of an old fur trading fort with a small museum
History Colorado Museum (Denver) — nicely arranged but shallow
Manitou Springs Cliff Dwellings (Manitou Springs) — reproductions of Native American cliff houses
Museum of Colorado Prisons (Cañon City) — located next to an operating prison
St. Elmo — ghost town near Buena Vista