Colonia Claudia Ara Agrippinensium
Germania Secunda, Germany
Colonia Claudia Ara Agrippinensium was the Roman colony in the Rhineland from which the city of Cologne, now in Germany, developed. It was usually called Colonia (colony) and was the capital of the Roman province of Germania Inferior and the headquarters of the military in the region. With administrative reforms under Diocletian it became the capital of Germania Secunda. During the second and mid-third centuries, around 20,000 people lived in the city. Many artefacts from the ancient city survive, including the arch of the former city gate with the inscription "CCAA", which is today housed in the Romano-Germanic Museum.
Archaeological site data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).