Berlin is the capital of Germany. The city has a very international feel and is nowadays a busy start-up hub in the country. While Berlin may not be the center for big German conglomerates, with Münich and Frankfurt taking some of those - there is still plenty of activity in the city.
The city is absolutely the most interesting city in Germany. With it's old history and a hip cool atmosphere, there is a lot to see and do within Berlin. This means that should your work trip be in Berlin, you should definitely stick around - whether you like partying or are a history buff.