Cartagena - Cartago Nova (Roman) - Qart Hadasht (Carthaginian) 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. This year, from September 16th to 25th.
"A disembarkment commemorates the taking of the city, in the year 209 a.c. by the Roman troops of Escipio. This is the reason of a festive week in which days dedicated to one side or the other alternate. The marriage between Hannibal and Himilce or the day of the Roman Circus, with its gladiators and wild beasts, are the pillars of a huge parade which takes place on Saturday (Saturday, 24th). This Saturday, 24th, will be the most important day of the festivity, when the troops and legions march through the city." (Source: murciaturistica.es)