Fonte.
Autodromo di Modena Made from scratch by Giuseppe Bernardi (aka Rigel) and Angelo Granata. How to install: Extract the "modena3" folder in C:\Program Files (x86)\Steam\SteamApps\common\assettocorsa\content\tracks, or wherever your AC folder is located.
download http://www.drivingitalia.net/forum/index.php?app=downloads&showfile=7514