1856 - Prior to completion.

(inset on right shows state of construction in 1817) The crane on the southern tower was the symbol for Cologne for over 400 years. (see description) There are no reports about the crane's construction, but it can be seen on a painting of around 1450. At the time of the painting, the crane had already been idle for a long time, so it's unlikely that it was built as late as the 1400's (which was formerly believed). It's more likely the crane was built and raised around 1350 when the building of the tower began.

blueprint and other specifications of crane at:
http://www.koelner-dom.de/domkran.html?&L=1