Hahnentorburg

The gate was built in the early 13th century as a twin-tower gate, similar in design to the surviving Eigelsteintor to the north and the demolished Gereonstor. In the Middle Ages, kings travelling from their coronation in Aachen would enter Cologne via the Aachener Straße through the Hahnentor and proceed to the Shrine of the Three Kings in Cologne Cathedral. The gate tower also served as a prison: in 1528, preachers Adolf Clarenbach and Johann Klopreis were incarcerated here; Klopreis escaped on New Year's Eve 1528, while Clarenbach was burned at the stake at Melaten Cemetery in 1529.

When Cologne began acquiring the fortification grounds in 1881 and dismantling its medieval city wall, the city chose to integrate only a handful of gate towers into the new urban landscape — the Hahnentor among them. City architect Josef Stübben restored it around 1890 and housed the Historical Museum within it, a forerunner of today's City Museum. The square to the west was renamed Rudolfplatz in 1883.

Severely damaged in World War II — the semi-tower on the outer left side was largely destroyed — the gate later served as an exhibition venue. Since 1988 it has housed the EhrenGarde der Stadt Köln 1902 carnival society and a casino. The Hahnentorburg is one of four surviving gate towers of Cologne's medieval fortifications, alongside the Severinstorburg, Ulrepforte, and Eigelsteintorburg.