There are 4 Midi files which drakkar calls whenever you are in a particular environment, whether it be town, battle, the wilderness or dungeons. You can change the music you listen to by replacing the files with other midi files and renaming them. I was always a fan of the midi music from Ultima 6 so here are the midi files from that great game.
http://www.wolfguild.com/downloads/midi ... u6midi.zip
Here is an additional link to a site with a lot of old game midi files you may enjoy hearing, just for nostalgia...
http://www.flyingomelette.com/midis.html