Mike Haydon asks about web sites offering downloadable public domain
music. A web search on the terms "free sheet music" will give lots
more hits than this one, which is one of my favorites:
Prowl the sub-directories, including one for public domain stuff.
Anything over 75 years old has to be public domain. Don't miss the
sub-directory /midifilesindx.htm (note the lack of "e" in "indx").
There is a link there to another web page offering dozens and dozens of
J. P. Sousa marches in MIDI format.
If your web browser supports 'frames', you'll be in musical hog heaven.