BTW I believe I am right in saying a DC3 crashed accidently into the Empire State building in the 40's and guess what, it didnt fall down
It was a B-25, actually. Presumably not bombed-up. But in any case, at a weight of, say, 25,000 lb and around 150 kt, it would have more than 20 times the impact energy of a 100 kt, 2400 lb light single.