Timgad or Thamugas, a Roman colonial town in Algeria was founded by the Emperor Trajan around 100 AD, as a military colony. Initially, it was largely populated by the Roman veterans of the Parthian campaigns who were granted landed property in return of their services for the Roman Empire. Constructed and designed for a population of around 15,000, the city was originally named 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). However, within a short time of its inception, the city madly outgrew its original plan and spilled beyond the specific grid. The ruins of Timgad, located in Algeria, 480 km southeast of Algiers and 110 km to the south of Constantine, represent an excellent example of grid plan, which the Romans used to follow while planning their cities.

Timgad continued to enjoy its peaceful existence for the first several hundred years after its inception and gradually became a centre of Christian activity. Its decline from the zenith began in 439 AD, when the Vandals invaded and plundered the city. In fact, it was completely destroyed and fiercely razed by the Barbers at the end of the 5th century and the Byzantine general Solomon found the city absolutely deserted, when he invaded Timgad in 535 AD. However, the Byzantine conquest of the city in 6th century gave it a new life as it was briefly repopulated. Unfortunately, the rejuvenation was short lived, as the Arab invasion brought about the ultimate ruin of Thamugadi and the city became deserted after the 8th century. Gradually, Timgad disappeared from the face of the earth and it became one the lost cities of the Roman Empire and its ruins remained hidden under the endless ocean of sand, till it was excavated in 1881.

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

The Capitoline Temple, dedicated to Jupiter, Juno and Minerva, was the most sacred place of the pagan worship and perhaps had the same dimensions as the Pantheon in Rome. Reached by a flight of 28 steps and enclosing a larger space than the forum, the impressive structure of the temple was completed in 160 AD.

Apart from the Celsus Library in Ephesus (Turkey), the Public Library in Timgad is recognized as the only other Roman-period public library. The library, measuring 61 feet by 77 feet (24.69 m by 23.47 m), is estimated to be dated back to the late 3rd or possibly the 4th century. The massive building consists of a huge semi-circular room flanked by two secondary rectangular rooms, which is preceded by a U-shaped colonnaded portico surrounding the three sides of an open court. It is estimated that the library could have accommodated around 3,000 invaluable ancient scrolls.

There was also an open theatre in Timgad, constructed by cutting into a hillside, with seating arrangements for around 3500 people in its rows. The various other buildings of the city, with different size and shape were ornamented with imposing mosaics.

The great baths of the city were symmetrically designed and were properly equipped with latrines, warm and hot rooms on either side of the complex, leading to a central Frigidarium, alias the cold room, elegantly facilitated with an icy plunge pool and a room off either end for relaxing after the bath.

Apart from the above structures, Timgad also had various other structures that characterised a Roman settlement. Most important among them is the Forum, used as a place for the selling of goods and for various social gatherings.

In the year 1982, Timgad was enlisted as a World Heritage Site by UNESCO.