Lighting is I think the most interesting and also the most challenging in Blender. Here are two of my latest Renders using HDR environment lighting instead of using the classical Sun, Spot and area lights. I always wanted to create a Cityscape and Interior Design in Blender but until lately I wasn’t really satisfied with my attempts, even after using Blender for several years. The City is mainly lighted by the emission shaders used on the buildings and in the interior scene I used Portal lighting which is available in Blender 2.75. Rendered with Cycles.
Wire frame with Portal lights.
Rendered Result 2000 Samples.