Firaxis has uploaded some of the music of the known antiquity and exploration age civs (some are currently being re-uploaded), and they seem very nicely themed. For the soundtrack discussion, please check this thread by our user Guandao.
For people interested in the background art, our user Rac has uploaded all the nice artwork, and you can find them now in our gallery here.
We also got today the official reveal of the Normans, although all the data has been collected before by our moderator Laurana Kanan. If you want to discuss all the Norman fortifications (as all their unique infrastructur and associated wonder are essentially that), then have a look here.