Space Shuttle Endeavour Rollout, 1991 "NASA Administrator Richard H. Truly addresses the audience in attendance at the rollout ceremonies of the Space Shuttle Orbiter Endeavour which occured on April 25, 1991, at the Rockwell International facility, Palmdale, Calif. Endeavour, the fourth Orbiter to join the fleet, replacing the lost Challenger, can be seen in the background."
Source: NASA on The Commons.