Cartagena was founded about the year 227 B. C. by Carthaginian general Hasdrubal. The Carthaginian presence in it would be fleeting because in 209 B.C., during the Second Punic War was conquered by the Roman Scipio.
This latter is what is commemorated during the festival of Carthaginians and Romans. Here you can view some videos.
The picture is really bad, I took from a local newspaper.