I still can't comprehend how the scientists and engineers managed to launch STS 1 (test flight) with two astronauts in 1981 - without doing a prior test launch with no astronauts inside (like SpaceX).. Absolutely incredible. I don't know what it is about the Shuttle, but the aesthetics are just really nice. The safety, of course, is a different question, but it still has a special place in my heart.