Nuketown has been one been one of the most well-known maps of the Black Ops series, since its introduction in Call of Duty: Black Ops. Now Treyarch is releasing the map and related personalisation pack for Xbox One, PlayStation 4 and PC for free if you hadn't already got them from pre-ordering the game starting today. This is a welcome change back to the norm after Sledgehammer games charged players to get Atlas Gorge if they hadn't pre-ordered or owned the Season Pass. Treyarch will also be adding a Nuk3town 24/7 sometime next week, while it is not stated it may also come with some form of double XP. There was no mention of the last-gen consoles so it may not be coming out for those, however this could change in time.
Reference: Activison blog