Timgad is a Roman-Berber archaeological site on the northern slopes of the Aurès massif in northeastern Algeria. The colony was founded around 100 CE by Trajan as a settlement for veterans of the Third Augustan Legion, on a site that already bore the Berber name Thamugadi.
The plan of the city is among the most complete examples of orthogonal Roman urbanism surviving anywhere in the empire: a near-perfect square divided by the cardo and decumanus into a regular grid of insulae, with a forum, basilica, library, fourteen public baths, and a 3,500-seat theatre. The Arch of Trajan still stands at the western entrance.
The city was sacked in the late fifth century, possibly by Vandal-allied Berber raiders, but Christian inscriptions show that a reduced population continued into the Byzantine reconquest. Definitive abandonment followed the seventh-century Arab conquest, after which the site lay buried under the sands of the Aurès foothills until its excavation by French archaeologists from 1881 onwards.
Timgad's Berber name and its position on the cultural-geographic line between the high Aurès and the Constantinois plain make it a key site in the Numidian-Roman synthesis. UNESCO inscribed Timgad as a World Heritage Site in 1982.