The Phoenicians and the Carthaginians, who founded several colonies in Morocco, inhabited the banks of the Bou Regreg approximately two kilometers from its mouth at the ancient site of Chellah. This archaeological site contains the ruins of a Roman town known as Sala Colonia and referred to as Sala by Ptolemy. Chellah was a significant ancient port city with remains including the Decumanus Maximus, or principal roadway, as well as a forum, a monumental fountain, a triumphal arch, and other Roman ruins.