Founded by the Emperor Trajan around 100 AD, Timgad or Thamugas was a Roman colonial town in Algeria. It was founded as a military colony and was largely populated by the Roman veterans of the Parthian campaigns who were granted landed property in return of their service. Originally, the name of the city was Colonia Marciana Ulpia Traiana Thamugadi, which is a fusion of the names of Emperor’s mother, Marcia eldest sister, Ulpia and father, Marcus Ulpius Traianus. Initially Timgad was designed for a population of around 15,000. But within no time, the city madly outgrew its original plan and spilled beyond the specific grid. Located in Algeria, 480 km southeast of Algiers and 110 km to the south of Constantine, the ruins of Timgad represent an excellent example of grid plan, as used by the Romans in the planning of their cities.

For the first several hundred years, Timgad continued to enjoy its peaceful existence and it became a centre of Christian activity. In AD 430, the Vandals invaded and plundered the city, and that marked the beginning of the decline. It was literally destroyed by the Berbers at the end of the 5th century. When the Byzantine general Solomon invaded Timgad in 535 AD, he found the city empty. The Byzantine reconquest in the 6^th century revived some activities in the city and it was briefly repopulated. But the Arab invasion brought about the final ruin of Thamugadi which ceased to be inhabited after the 8th century. Timgad disappeared from history, becoming one the lost cities of the Roman Empire. It remained hidden under the endless ocean of sand, until its excavation in 1881.

The city of Timgad, situated 1000 m above the sea level, was walled but not fortified. The design of the city was based on the magnificent Cardo and Decumanus system – north-south and east-west oriented streets running through the city, lined by a partially restored Corinthian colonnade. The streets were paved with large rectangular limestone slabs. At the west end of the Decumanus stands 12 feet high above the city, a triumphal arch, known as the Arch of Trajan. Constructed in the Corinthian order, the sandstone structure still dominates the ruins of Timgad.  Also known as the Timgad Arch, it consists of three arches, with the central arch being 11 feet wide. It was partially restored in 1900.

The Capitoline Temple of Timgad was dedicated to Jupiter, which probably had the same dimensions as the Pantheon in Rome. The great baths of the city were designed symmetrically, with the same latrines, warm and hot rooms on either side of the complex, leading to a central Frigidarium, the cold room with an icy plunge pool and a room off either end for relaxing after the bath. Apart from the Forum, there was an open theatre, created in the 160s by cutting into a hillside and had seating arrangements in its rows, for as many as 3500 people. The other buildings of the city, with various sizes and shapes, dazzle by their imposing mosaics.

The capitol was dedicated to the gods Jupiter, Juno and Minerva. This was the most sacred place of the pagan worship and, when it was completed in AD 160, the most impressive, enclosing a larger space than the forum, reached by a flight of 28 steps.

The Public Library in Timgad is only one of the two known Roman-period public libraries, the other being at Ephesus. It is suggested that the library dates from the late 3rd or possibly the 4^th century. Measuring 61 feet by 77 feet (24.69 m by 23.47 m), it consists of a large semi-circular room flanked by two secondary rectangular rooms. This is, however, preceded by a U-shaped colonnaded portico surrounding three sides on an open court. It is estimated that it could have accommodated 3,000 scrolls.

Timgad was inscribed as a World Heritage Site by UNESCO in 1982.