In order to capture the dynamic lighting of a city at night (e.g. dark corners vs. bright lights), a technique called 'tonemapping' can be used. Essentially it works by taking three (or more) identical photos with different exposure times. These images must then be processed in special software to create a single image that basically contains the combined brightness information of the original photos. Without this procedure either the forest in this particular photo would appear completely black or the buildings would be overexposed.