Slyke, Lyman P. van. 1988. Yangtze: Nature, History, and the River. Reading, MA: Addison-Wesley.

Timgad, Algeria

The Roman town now known as Timgad was founded in A.D. 100 on command of the emperor Trajan (reigned 98–117) and named Colonia Marciana Trajana Thamugas for his sister. It was built on a high plateau north of the Aurès Mountains in Algeria (then Numidia), 94 miles (150 kilometers) south of the modern town of Constantine. The Third Augusta Legion, effectively the Roman police force in North Africa, was garrisoned nearby, and Timgad, designed for veterans, was the archetypal Roman colony. The regular well-ordered layout became one of the principal sources of city plans in Europe and the New World from the fifteenth century until the beginning of the twentieth. It is therefore significant in the development of Western architecture and urban design. In turn, the inspiration for Timgad comes from the Roman army encampment, the castrum.

Perhaps because it was easy to set out, or perhaps because it suited military purposes, the right-angled grid formed the structure of the castrum, which might have served as a garrison for months or even years during a campaign. Two main streets, the Via Principia and the Via Praetoria, intersected at the legion’s command post. Both extended through fortified gates beyond the enclosing ditch and palisade. Many permanent towns later grew from a castrum; for example, most English cities with “chester”—Winchester, Silchester, Dorchester—in their name have such origins, and in places like Chester the Roman plan is easily discernible. Even when they were building on a completely new site, Roman civil engineers used a similar grid (orthogonal) plan.

The hills around Timgad were once savanna grassland, and the mountains bore conifer and evergreen forests. Numidia was fertile and productive, and the prosperous province of Africa, of which it formed part, became known as the granary of Rome, furnishing a large proportion of the capital’s barley, figs, and olives. Large olive presses have been found in and near Timgad. The town was essentially a 1,000-foot-square (300-meter) walled enclosure with gates on three sides. Its two main streets, a north-south cardo and a colonnaded east-west decumanus maximus, formed a T-junction almost at the center of the town, at the paved, colonnaded forum. At the western approach to the decumanus, just outside the wall, stood the tripartite Arch of Trajan, dating from the third century a.d. The plan was divided into 132 square blocks (insulae), separated by 16-foot-wide (5-meter) paved streets, underneath which sewers ran. The insulae contained 400 houses, some of which were large enough to occupy a whole block, as well as shops and taverns. Timgad boasted twenty public buildings. In the forum there was the curia (council chamber), the basilica (town hall), a temple, shops, and a public lavatory. Just south of the forum, hollowed out of a low hill, stood a theater designed to hold up to 4,000 people. Other buildings, such as a library and public baths—there were seventeen of them, some quite extensive—were dotted around the town, both within and outside the walls. An aqueduct supplied water to Timgad from a spring about 3 miles (5 kilometers) away. There were also two large markets, one at either end of the decumanus. The large Temple to Jupiter Capitolinus stood outside the walls at the southwest corner of the town.

Almost inevitably, Timgad outgrew its walls. Some estimates put the eventual population at 15,000. The first extensions seem to have followed the orthogonal pattern of the original plan, but soon rather untidy development of “extensive but casually laid-out ‘suburbs’” occurred along the arterial roads to the neighboring colonies. Timgad was a center of Christianity in the fourth century and became a stronghold of the Donatist heresy. With the decline of the Roman Empire it lost much of its significance. It was successively despoiled by the invading Vandals in the fifth century, the Berbers in the early sixth, and the Arabs in the eighth. Timgad remained in Arab hands until the French annexation of Algeria in 1830. It was forgotten until the end of the nineteenth century, and protected by isolation and the encroaching sands of the Sahara; then investigations were begun by the French architect Albert Ballu for the Service des Monuments Historiques de I’Algérie. The ancient city was inscribed on UNESCO’s World Heritage List in 1982.