Colonia Claudia Ara Agrippinensium (English: colony of Claudius and altar of the Agrippinians) was the name of the Roman colony in the Rhineland that was lather to become the modern city of Cologne. The inscription S / COLONII / A on the reverse of this medieval pfennig still relates to that name (Sancta Colonia Agrippina).
Emperor Otto the Great (936-973) had reestablished a mint in Cologne, and commissioned it to issue pfennigs with the traditional Colonia monogram. Since then Cologne was one of the major mints in the Holy Roman Empire, and the Cologne pfennigs were frequently copied.