Founded by the Numidians as a fortress town for defense, by 46 BC Maktar had become a free city. By 146 AD it was a Roman colony.
From Schoder's lecture notes:
Phoenician. Rom. colony
Mactaris 2nd half of 2 c.
Forum, Arch Trajan, Baths (at back): arch 116 AD
Pyramidal mausoleum, frt., at necropolis edge