Fossatum Africae – Reminders of Roman Empire History

Thought to measure 750 kilometers or more, the linear defensive structure known as Fossatum Africae was built during the rule of the Roman Empire as a measure to both defend and control the southern borders of its interests in North Africa. The four preserved sections of this historic structure are found in Algeria and neighboring Tunisia, remaining as a reminder of a time in history when the Roman Empire appeared to be unstoppable in its conquests.

The only written reference discovered by researchers and scholars of the Fossatum Africae, literally meaning ‘African ditch’, is found in the compilation of Roman Empire laws known as Codex Theodosianus dating back to 312 AD. The reference is found in a letter to Roman citizens living in Africa, from the co-ruling Roman emperors of the time, Theodosius and Honorius. The letter states that if Roman citizens did not continue to maintain the fossatum, then the job would be given to barbarian tribes that had proven to be friendly to the Roman Empire. Along with the loss of employment, Roman citizens would lose land rights and other benefits that went with maintaining the defensive structure. From the tone of the letter it appears that the Fossarum Africae had already been constructed and was in need of maintenance, but it is unclear as to when the original construction took place – although it is agreed that with a structure of this magnitude it most likely took many years to complete and was done in stages.

Based primarily on the similarities between the Fossarum Africae and Britain’s Hadrian Wall, French pioneer of aerial archeology, Jean Lucien Baradez (1895-1969), was of the opinion that the construction most likely started after Emperor Hadrian visited Africa in 122. His aerial photographs of the archeological sites remain the most comprehensive record of this historical structure.

The Fossatum Africae consists primarily of ditches with earth embankments on either side, with some sections including dry stone walls on top of the embankments. The widths of the ditches vary between three and six meters and are as wide as twenty meters in some places. Near the Roman fort and camp located at Gemellae on the edge of the Sahara Desert in Algeria, excavations have revealed that the ditch depth is between two and three meters, with the bottom measuring one meter, widening to two or three meters at the top. There are watchtowers and forts at regular intervals along Fossatum Africae. Similar structures have been found in other North African regions, including the fossatum found at Bou Regreg in Morocco.