Timgad lies on the northern slopes of the Aurès mountains and was created ex nihilo as a military colony by the Emperor Trajan in AD 100. With its square enclosure and orthogonal design based on the cardo and decumanus, the two perpendicular routes running through the city, it is an excellent example of Roman town planning. Located at the intersection of six roads, the city was walled but not fortified. A 3,500-seat theater is in good condition and is used for contemporary productions. The other key buildings include four thermae, a library, and a basilica. Timgad was inscribed as a World Heritage Site by UNESCO in 1982.