Wow, it just sunk in for me just how amazing the soundtrack for Cvilization IV is.
After playing awhile, I started to recognise some of the music that was woven into the background music. Then, I started recognising a lot of the music. So, I decided to hunt in the program's directories to see if the music was accessible; it is.
It turns out that all the music are just regular mp3 files, and there's a lot of them. Some of the music pieces are original comppsitions, but most is selected pieces representative of the great works over many musical eras. There's Bach, Brahms, Dvorak, Palestrina, Mozart, &c (no Schubert?) and the treatment of each is quite excellent.
Thus, there's a new batch of 75 mp3 files running through my iTunes library. Not a bad little bonus that comes with the game.