The hill of Muru Mannu occupies the northern sector of the city of Tharros. It is affected by a stratigraphy documenting settlement phases ranging from the Middle Bronze Age to the Byzantine Age. The settlement of round huts arranged around a nuraghe was partially used by the Phoenicians for the creation of the tophet from 620 BC. The whole area undergoes radical changes in the Carthaginian period with the renovation of the tophet and the impressive fortifications that were renovated during the Late Republican period. Between the second and the third centuries AD, the top of the hill is affected by the installation of a circular structure recognized as an amphitheater. Here , in a sector of the cavea, a research of the School of Specialization in Archaeological Heritage of the University of Sassari in 2013 has started. The objective of the survey, just begun, is to check the exact date of construction of the amphitheater and its possible overlap with the previous levels of tophet and protohistoric settlement . The data collected so far seem encouraging: it seems to specify a terminus post quem for the construction of the amphitheater between the late second and the third centuries AD while fragments of urns, Phoenician and Punic amphorae and a fragment of a mask suggests the probable existence of the remains of the sanctuary below the amphitheater.