The Roman city in Algeria founded by Emperor Trajan and laid out on a grid plan is Timgad.
Trajan founded Timgad around 100 CE as a colonia for Roman military veterans in the Aurès Mountains of eastern Algeria. Its official Roman name, Thamugadi, reflects the site’s North African setting, while its remarkably regular streets show the Roman preference for organized urban planning.
The city was arranged around two main avenues, the north-south cardo and east-west decumanus, which divided the settlement into rectangular blocks. Timgad developed with a forum, basilica, temples, baths, markets, a library, and a theatre. The surviving street grid makes it one of the clearest examples of Roman town planning in North Africa.
Timgad prospered during the Roman and later Christian periods before being gradually abandoned after political and economic changes in late antiquity. It is sometimes confused with Djemila, another spectacular Roman site in Algeria, but Djemila is the ancient city of Cuicul and was not Trajan’s grid-planned colony. Timgad has been a UNESCO World Heritage Site since 1982.