Any maps that were made for the original Red Alert 3 will work in the expansion RA3: Uprising. You can simply download custom made maps and place them in your Uprising map folder. Also, thanks to Alex06, you can download all of the original Red Alert 3 maps that were included with the game, place them in your Uprising map folder, and play those maps in skirmish mode for Uprising. There's 20 maps in total, which includes all of those special bonus maps that can be played in Uprising. You can download them from the link below.

Download this 20 map pack for Uprising HERE >  (17.7MB)