Nucleus of urban development in the Middle Ages

In addition to the Bonnburg and the trader’s settlement "Vicus Bonnensis” the area around the grave chapel of the saints Cassius and Florentius, at the point where the Münster Basilica now stands, became increasingly significant. As the guardian of the Martyr’s church the Cassius’ foundation was first mentioned at the end of the 7th century, which constructed an foundation church at the site of the grave chapel around 780 AD. At the start of the 9th century the name “Villa Basilika” appeared for the first time for the settlement that was still unfortified next to the foundation church.

The Norman raids in 881/82 AD caused a great amount of devastation. Whilst the old settlement next to the Dietkirche (church of the people) hardly recovered from the damage caused, the foundation area was fortified. In addition the Cassius’ foundation gained a lot of influence due to the large amount of donations made.

At the turn of the millennium the main point of settlement was shifted towards the “Villa Basilika”. Before its walls the open market settlement "Oppidum Bonnense" came into being in the direction of the Rhine, which was officially mentioned for the first time in 1211, with a large market place as its focal point. The actual emergence of the city of Bonn stemmed from these two nuclei of the foundation area and the market settlement.