Resumen
Timgad lies on the High Plateau of the Aurès Mountains in northeastern Algeria, 35 km east of Batna, at an altitude of 1,050 m. It was founded as a veterans' colony by the Emperor Trajan in 100 CE and formally named Colonia Marciana Ulpia Traiana Thamugadi in honor of Trajan's sister Marciana. The location was strategic: the Aurès served as the mountain redoubt of the Berber Chaouïa people, and the colony was designed to anchor Roman control of the southern frontier.
Timgad is the most completely preserved example of Roman urban planning anywhere in the empire. The original colony was laid out as a perfect square of 355 m × 355 m, divided by a regular grid of cardines and decumani streets into 111 identical insulae (city blocks). Later growth expanded the city beyond the original plan, adding irregular suburbs, but the colonial core survives with extraordinary completeness: the paving of the decumanus maximus is intact for its full length; the Trajan's Arch at the western end stands nearly to its original height; the forum, basilica, and Capitoline temple occupy their exact positions at the crossing of the main streets; and the theatre, with a 3,500-seat cavea carved into a hillside, retains its seating tiers and stage-building walls.
The city reached its height in the 2nd and early 3rd centuries, when it supported a population estimated at 15,000–20,000. Twenty-three bath complexes have been identified, an extraordinary number even for a Roman city of this size. A large Christian basilica of the 4th century — one of the largest in Roman Africa — reflects the city's conversion after Constantine. The city was sacked by the Berber king Tacfarinas in the 5th century, partially reoccupied, and finally abandoned when advancing Saharan sands buried the southern portion to a depth of several meters — an accident of preservation that explains the remarkable completeness of what survives.