Fossa regia

The Fossa regia was the first part of the Limes Africanus to be built. The fossa was an irregular ditch "from Thabraca on the northern coast to Thaenae on the south-eastern coast" dug by the Romans after their final conquest of Carthage at the end of the Third Punic War in 146 BC. The construction's primary purpose was administrative, not military. It delineated the limits of the newly created Roman province of Africa marking the border between the Roman Republic and its then ally Numidia.

After 46 BC, the western part of the Fossa regia served as the boundary between the Province of Nova Africa, to its west, and the province of Africa vetus to its east. Even after these two provinces were merged into Proconsular Africa in 27 BC, the ditch continued to be maintained as late as the year 74 AD under the emperor Vespasian.