Tébessa (təbĕsˈə) [key], ancient Theveste, town (1998 pop. 153,246), NE Algeria, in the Atlas Mts. The town is an important agricultural market and is noted for its silk embroidery and carpets. The surrounding area is an important phosphate- and iron-mining region. Extensive ancient remains include the Roman Arch of Caracalla, a Christian basilica (c.4th cent. A.D.), and restored Byzantine walls and temples.