Source
Source: REGIERUNGonline/Schambeck
Chancellor Helmut Kohl (right) and Prime Minister of Brandenburg Manfred Stolpe (left) sign the Capital City Treaty [Hauptstadtvertrag] in Berlin City Hall. The treaty regulated the cooperative efforts of the federal government, the Berlin Senate, and the federal state of Brandenburg, all of which participated in transforming Berlin into the new capital of the Federal Republic.
Source: REGIERUNGonline/Schambeck