Peterson Air & Space Museum, Colorado Springs (always free)               

The Peterson Air and Space Museum has one of the better displays of vintage and historic military aircraft in the western United States.

Planes are on display in an approximately 8 acre outdoor area on Peterson Air Force Base. Two indoor areas provide additional exhibits about World War II and current defense systems.

Now compared to the National Museum of the U.S. Air Force at Wright-Patterson in Ohio, or the Smithsonian National Air and Space Museum, the Peterson Museum displays are very limited. So I wouldn't go out of your way to visit this museum. However, if you are in the Colorado Springs area and like to view vintage aircraft, a trip to the Peterson Air and Space Museum should definitely be on your list of things to do.

Access to the museum is easy if you or someone in your group has a military identification or DoD card. If not, prepare to jump through some rather extensive hoops to gain access to the museum. This is because the museum is located on a highly secure U.S. Air Force military base, and there isn't a public entrance like there is at Wright Patterson. 

Hours
9 am to 4 pm Tuesdays through Saturdays.
Not open on Sunday, Monday or Holidays.

Location
7 miles east of Colorado Springs.
Peterson Air Force Base Building 981 (Peterson Blvd and East Ent Ave.)
Enter at the Peterson West Gate near Powers Blvd and Airport Road.

How to obtain access to the museum (important info, read a few days before you go):