From Wembley Stadium to Heathrow Airport, Project London is bringing the British capital's iconic landmarks to life in GTA 5.
GTA has become widely popular and known for critiquing and satirizing typical American pop culture and society, with fictional versions of the most famous cities in the USA serving as locations for the games. However, the franchise has actually gone international in the past, and one of the most ambitious modding projects wants to take GTA back to London.
GTA London was an official expansion pack for the first GTA game, taking players to the British capital during the '60s. It was the series' only outing in another nation other than the USA, but has been the source of many rumors about a return to London in the decade since.
A group of skilled fans, however, has decided to take things into their own hands and develop a total conversion mod that brings a fictionalized version of London to GTA 5. The mod support and technical capabilities of the current game could make this the definitive return to London, lest Rockstar actually give us an official game set in the city.
Pulling this off is a massive task. The team, headed by Kieran Merrilees, isn't planning on making a fully accurate recreation of London, since that would be nigh impossible even for a full development team, let alone a group of fans doing this in their free time.

They're building a city "like London", with all the important landmarks and rough matching layout, but taking several liberties with it. It's unclear whether they will attempt to alter the side on which cars drive to match the inverted roads of Britain, however Kieran approximated achieving that would require 210 man-hours of work, and isn't a terribly high priority.
To get something so seemingly simple done, the pathfinding of all NPC vehicles would need to be rewritten, which is a massive task considering you need to meddle with the AI programming without messing up everything else. However, the team is focused on other, more tangible tasks for now.
What makes a virtual city instantly recognizable isn't the street layout, but the landmarks. Currently, the team of just three developers are putting together accurate models of some of London's more notable buildings and placing them in the default Los Santos map.