Today was open house day at the Deutsche Bundesbank, the german federal reserve bank, in Frankfurt.
Since the Bundesbank is a federal agency it flys the Bundesdienstflagge, the federal service flag, which is the national flag only agencys of the german state, like federal ministries and gouvermential institutions, the Bundeswehr (german military) and the Bundespolizei (federal police) are allowed to fly. It is the black red gold tricolour with the coat of arms.