Cities: Skylines launched on Tuesday and already someone has gone ahead and re-created Los Santos in it, trumping the thrice-delayed PC release of Grand Theft Auto 5 (which is due in 31 days).
The map lacks some of the features of the in-game city — no chairlift on Mount Chiliad, no Ferris Whale at the Del Perro Pier, for example. But topographically, and with regard to the cities' planning and street layout, it's astonishingly accurate. See for yourself above.
It's the work of Steam user grockefeller. You can grab the mod for Cities: Skylines here.
For non city-planners on the PC, your exploration of Los Santos will begin April 14. That should open the floodgates on a ton of mods, too. For more on Cities: Skylines, check out this overview video.