The Brandenburg municipalities of Alt-Berlin and Cölln had received town privileges in the 13th century and from 1307 on shared a common administration, but were divided after the elector subjected the city (following the idea of divide and rule) and made it his residential city in 1448. King Frederick I of Prussia by resolution finally had both towns, and three later founded adjacent cities,[3] merged and elevated to the "Royal Capital and Residence City of Berlin" as of 1 January 1710.