If I remember correctly someone jumped it many years ago. I think I saw a picture of it in Skydiving Magazine before I even started skydiving. Is it something on the order of 570 some odd feet tall? If so then yes it's been jumped before by someone.
Bill L. did the San Jacinto Monument in Texas and the picture looks a lot like the other thing. That may have been what you saw. In 1991 I was being driven around D.C. at night by Bill Ottley (then executive director of the USPA) and I was sitting on the trunk lid of his flaming (red or yellow?) Cadillac convertible drinking a beer. When we passed the Washington Monument he caught me eyeballing it and said, "Don't even fucking think about it."
If the Washington Monument has been done, it was done right, as I've never heard about it from anyone . . .
Are you sure? I'd bet money I saw a picture of it and the caption said it was the Washington monument. A guy jumped from some window up at the top of something. 575' rings a bell. I'll see if I can find that magazine.