The only things I remember is that it was 2 boys who were friends and they go on some kind of adventure, and I think at one point there’s a falling out and one has to rescue the other. I remember Woodrow Wilson being mentioned, and at one point they were in a large hall of sorts, because that’s where I first learned the term “flying buttresses.” I read it in the 90s but not sure of the pub date. I remember a dusty purple color but that’s it. This has plagued me for years!