Chromological U-bahn

With its ten lines, the U-Bahn (underground, subway) Berlin runs along a network of approximately 146 kilometres and includes 173 stations. Most metro lines operate underground, but some run on above ground tracks. The U-Bahn Berlin is known for its yellow-colored trains and colorful stations.
Chromological U-bhan project is about chromo (color) and order. During my first-ever visit to Berlin I stopped over 20+ stations (only!) to document a project I had in mind even before the visit. It is an ongoing project as I have only stopped over 11% of all U-bahn stations due to a lack of time during my visit.