Incredible engineering effort considering it was designed in the early 60’s, and incredible pilots who flew them.
I was fortunate enough to work in the corporate world for a retired 3 Star who was a U2 / SR driver who later commanded the 8th Air Force. Hands down the best manager / leader I had ever worked for directly, developing complex government comms systems with many challenges. When someone brought up a serious challenge in the development, he would gather all the info, ask about alternative paths, then tell a reeeeeel pucker factor story, like flying across a denied area when one engine “unstarts”, then having RWR scream you got 2 telephone pole sized objects coming at you at twice your speed. Then ask which is a more difficult problem to solve.
Great leader.