The main elements of the city were modeled and rendered in 3dsMax. In the first image, these were a plain untextured surfaces, that were later textured & retouched in Photoshop. The second image was rendered with some basic textures on the elements. They also needed some later retouch & more detailed texturing in Photoshop.
Some additional elements were made from scratch in Photoshop (bike, entry doors, road signs, birds etc.) & in 3dsMax (trash bin) while the tree & a little wrinkled piece of trash were a paper cutout shot in the studio.
Below: wireframe models of the city in 3dsMax