A city drawn on a grid
Timgad, in the Aurès region of northeastern Algeria, is often shown in books as the clearest example of Roman town planning. Its ancient name was Thamugadi. The founding of the city is dated to about 100 CE, under the emperor Trajan, and the layout was set out at once rather than growing over centuries. The result is a plan that archaeologists can read directly from the ground.
The original city was a square of roughly 350 metres on each side, divided into regular blocks by streets that cross at right angles. Two principal streets form the axes. The cardo ran north to south and the decumanus east to west, and their meeting point lay close to the forum. The streets were paved with stone slabs, and the blocks between them were divided into building plots. The idea was not new, since the grid plans used in Roman colonies drew on Greek and Italian precedents and on the layout of army camps. Many scholars see the overall resemblance to Roman marching camps as a sign of the military origin of the founders, though the plan was also a practical tool for allotting land fairly. Other early cities used grid layouts too, as in the Lower Town street grid of Mohenjo-Daro, but those were independent traditions, far removed in time and place.
Grid planning gives Timgad an unusual clarity. A visitor can follow the colonnaded main street, find the blocks of houses, and see how public buildings fit into the pattern. Over time, however, the city grew beyond its original walls, and the later quarters are less regular.
The forum and public buildings
At the heart of the city lay the forum, a rectangular open space paved with stone and surrounded by porticoes. It was the centre of civic life and held the basilica, a hall used for law and business, as well as the curia, where the town council met. Statues and inscriptions honoured emperors and local benefactors. Nearby were a market and temples, among them a Capitolium dedicated to the main gods of Roman state religion.
The theatre was built into a slope on the southern side of the city. Its seating was carved in a semicircle around the performance area, and it could hold several thousand spectators, although exact figures vary. Like many theatres across the empire, it followed the standard Greco-Roman form, with a stage building behind the actors. Its size shows that a town founded for settlers quickly acquired the amenities of Roman urban life.
Timgad also had numerous baths, often listed as more than a dozen, and they were among the places where residents met each other. The Roman public baths were a typical feature of towns across the empire, and the number built at Timgad suggests a prosperous community, though the exact total depends on how excavators count smaller complexes.
The arch and the library
The most photographed monument is the arch at the western end of the decumanus, often called Trajan’s Arch. It has a large central opening flanked by two smaller ones, with columns and niches for statues. It was probably built in the second century CE, and it stands at a place that may once have marked the edge of the original city. Despite its name, the arch was likely constructed later than Trajan’s lifetime, and the link with the emperor honours the city’s founder.
A library was added in the third century CE, according to an inscription naming a wealthy citizen, Julius Quintianus Flavius Rogatianus, as its donor. The building has a semicircular reading area with niches for book cabinets. A figure of thousands of rolls is sometimes cited for its capacity, but this is an estimate rather than a certain count. Libraries on a grander scale are known in Anatolia, from the Library of Celsus at Ephesus to the earlier Pergamon library. Timgad’s library shows that reading and literary culture reached even a small colony in the North African interior.
Why Timgad matters for Roman planning
Many Roman cities were built on older foundations, which obscured any plan. Timgad was a new foundation, then abandoned, which is why its structure remains legible. It lets scholars see how Roman engineers and surveyors translated an idea into stone: measuring blocks, laying out streets for drainage, positioning civic buildings at the centre and leaving room for later expansion.
At the same time, the picture should not be too tidy. The later city added irregular streets and large buildings outside the original square, and inscriptions show how local wealthy families paid for improvements. The site was surveyed and cleared by French archaeologists from the late nineteenth century onward, and today it is a UNESCO World Heritage Site. Some areas look more complete than they were in antiquity because of restoration work and the removal of later deposits. As a study of how a grid-based city worked, though, Timgad remains one of the best places to see it.