The world of Liberty City was to not only look alive, but also feel alive. This was achieved both by visual cues such as the dirt and decay that make it feel so lived in, the effects of years of use and misuse, and also by putting into that environment its own weather systems, day and night time ambiences, a population who respond to both, along with all of the human scale modifications to the built environment - thousands of advertisements from billboards to fly posters, for hundreds of brands, a full media system including radio and a functioning internet that people can use to discover things to do in the world in their down time. For the beauty of the world to have any meaning, people would have to have fun when they visited. New York is the most fun city on the planet, so it was felt that Liberty City would have to be the most fun digital city ever created, so it is full of distractions for the visitor looking for a good time.

In order to create a city at once so visually detailed and full of life, it was necessary to undertake research on a scale never previously seen before. Along with multiple research trips by the art team from Rockstar North, and the expertise of the members from years of living in New York, Rockstar utilized a full-time research team to photograph and video every aspect of the city. Not only building fronts, fire hydrants, roads and sidewalks, but also lighting changes across day and night, vehicle and pedestrian patterns throughout the day, the racial and social make-up of different neighborhoods and boroughs, the sounds of specific foghorns in the harbor, all combined to make a completely integrated world that continuously seems alive and natural in a way that was not possible in previous games. Local experts were interviewed and consulted on every detail to make sure Liberty City feels real to the player