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, 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. A Germanic tribe known as the Eburones had originally inhabited the present-day Cologne Lowland.
But they were wiped out in a war of reprisal carried out by Julius Caesar. This brought the Ubii within Roman-occupied territory. The Ubii chose an island in the Rhine as the central location of their settlement area. The island was a natural rise that was protected from flooding.
The location of the settlement no longer exists today but it roughly comprises the area between the areas of the Heumarkt and the Alter Markt sections of the old city of Cologne. The settlement can be dated by archeological finds to the first half of the 1st century AD.
By this time the typical Roman grid-style street plan was already in use. The settlement's assumed name is probably Oppidum Ubiorum Settlement of the Ubii. The Roman epoch of the history of the city of Cologne begins with this oppidum. The noble Segimundus is mentioned as the priest of the Ara in the year AD 9.
