Global illumination techniques have briefly been addressed to urban renderings. To the best of our knowledge, the algorithm we present in this master thesis is the fi rst one to compute nocturnal global illumination of a city in real time. As the problem of simulating nocturnal illumination of a city is to compute a high number of light sources, our technique divides the problem in two situations. First, for aerial views, we compute a rough simulation for the whole city and store it in a light map. For pedestrian views, we use a variation of traditional photon mapping technique to simulate global illumination of the user nearest subset of street lights. An integration method, inspired in the push-pull technique from hierarchical radiosity, integrates both solutions transferring information from one to the other to improve both of them. Our algorithm provides e ficient rendering during walkthroughs and y-throughs computing high quality images in real time.