Cities will increasingly play an important role in addressing the challenges of climate change. The German capital city Berlin is used as an example to illustrate that even large urban areas can achieve climate neutrality. Among the key elements for achieving climate-neutrality are solar energy and combined heat and power generation, the use of which will enable the city to generate a large amount of the required energy itself. This contribution reflects the main results of a feasibility study, which determined in detail how climate neutrality can be achieved and what must be done for it.