Cölln
Cölln () was the twin city of Old Berlin (Altberlin) from the 13th century to the 18th century. Cölln was located on the Fisher Island section of Spree Island, opposite Altberlin on the western bank of the River Spree, until the cities were merged by Frederick I of Prussia to form Berlin in 1710. Today, the former site of Cölln is the historic core of the modern Mitte locality of the Berlin-Mitte borough in central Berlin. History Cölln is first mentioned in a 1237 deed, denoting a priest Symeon of Cölln's (Symeon de Colonia) Saint Peter's Church as a witness. This date is commonly regarded as the origin of Berlin, though Altberlin on the eastern bank of the Spree river was not mentioned before 1244 and parts of modern Greater Berlin, such as Spandau and Köpenick, are even older. Cölln and Altberlin were separated only by the river Spree, linked by the Mühlendamm causeway, hence there was a close connection right from the start. Since the trade route from Magdeburg to Frankfurt (Oder) crosses the twin town and the inland water-transportation routes also passed through it, Cölln-Berlin quickly came to prosperity. A second crossing, the Lange Brücke (Long Bridge), today