"Köln" was ordered as "Cruiser D" under the contract name "Ersatz Arcona", as a replacement for the old cruiser . The keel for "Köln" was laid on 7 August 1926 at the "Kriegsmarinewerft" shipyard in Wilhelmshaven. She was launched on 23 May 1928, and commissioned into the "Reichsmarine" on 15 January 1930, the last member of her class to be completed. She spent the year conducting sea trials and training in the Baltic Sea. In 1931, she was modified with dual 8.8 cm anti-aircraft guns to replace the original single mounts, the rear superstructure was enlarged, and a fire control system was installed aft. "Köln" departed on a cruise into the Atlantic in early 1932 for more extensive sea trials. After returning to Germany, she took on her first crew of naval cadets for a world cruise, departing Germany in late 1932. The tour lasted a full year; she stopped in ports across the globe, including in the Atlantic, Pacific, and Indian Oceans, and the Mediterranean Sea. In Australia the tour stops included Adelaide, Melbourne, Sydney and Hobart, with the crew taking place in several publicised football games against local teams that included a Royal Australian Navy team in Sydney.