Districts of Cologne within city limits), while 174,87 km² (43.2 percent) lie right of the Rhine. In regard to population, Cologne is the largest city in the state of North Rhine-Westphalia and the fourth largest city in Germany. Since the city's foundation in 38 BC, Cologne grew through numerous extensions and incorporation of surrounding municipalities. Since the construction of the Medieval wall in 1180, the area of the old imperial city of Cologne has not changed for more than 600 years and was only extended over the old city walls in 1794, just short before the arrival of French troops and Cologne's incorporation
Demographics of Cologne over the old city walls in 1794, just short before the arrival of French troops and Cologne's incorporation into the First French Empire. After 1815, the Kingdom of Prussia enforced the construction of fortifications which again hindered any growth for the city. Only with the acquisition of these fortifications in 1881, the city of Cologne had the possibility of a gradual territorial expansion. On 12. November 1883 a strip of territory from parts of the municipalities of Ehrenfeld, Kriel, Longerich, Müngersdorf and Rondorf was added to the city. Since 1886, the Cologne City Council intensified negotiations with the surrounding communities,