an academy just like those already existing in London, Paris and Rome – the Prussian Academy of Sciences (originally German name: ″Kurfürstlich-Brandenburgische Societät der Wissenschaften″), based on the plans of Gottfried Wilhelm Leibniz. Leibniz became the first president of the Academy. The fees resulting from the calendar patent were the almost single financial basis of the institution for a long period. The society originally had no actual observatory of its own and Kirch carried out his observations at various private observatories including, from 1705, the private observatory of Geheimrat Bernhard Friedrich von Krosigk on the Wallstrasse, in Cölln. Kirch was assisted by his wife Maria Margarethe and his son Christfried. Maria Margarethe discovered, among other things, the comet of 1702. In the meantime the Kurfürst had been raised in 1701 to the rank of King in Prussia. On 1 January 1710, the capital was expanded by uniting the previously independent towns of Dorotheenstadt, Friedrichstadt, Friedrichwerder, and Cölln and Berlin (the oldest ones). The Old Berlin Observatory The first Berlin Observatory was sited in the Dorotheenstadt quarter. The Marstall Unter den Linden had been erected from 1687 to 1688 according to the plans of the architect Johann Arnold Nering, originally for 200 horses, and a second storey was added from 1695 to 1697 for the Academie der Mahler-, Bildhauer- und Architectur-Kunst, founded in 1696. From 1696 to 1700, Martin Grünberg extended the complex northwards for the new Societät der Wissenschaften, doubling the perimeter out to the Letzten Straße (later: Dorotheenstraße)). From 1700 until 1711, the observatory, a tower built by Grünberg with three levels, was added to the northern wing of the installation. The 27-meter-high building was one of the first tower observatories of the 18th century. The observatory became partly usable in 1706 and by 1709 was more or less completed. On 15 January 1711 the ″Königlich Preußische Sozietät der Wissenschaften″ held its first meeting in the tower and four days later its first formal gathering, at which the observatory was officially handed over. It became an important focus of the Society. In time, its library and natural history collection also came to be housed under the same roof. The Society was reorganized by Frederick II in 1744 as the ″Royal Academy of Sciences″ (″Königlichen Akademie der Wissenschaften″) and retained its base there until 1752. Gottfried Kirch died in 1710, a year before the official opening of the Academy and