ONE OF THE MOST significant discoveries of the Corinth Computer Project, as a part of the study of the city and landscape of the Roman colony of Corinth, Greece, has been the identification and discussion of two systems of centuriation, Roman urban and rural land planning.2 This work was carried out by teams of Roman agrimensores, or land surveyors, who are known to have been active in various parts of the Roman Empire over many centuries.3 We know that they worked at Corinth in connection with the planning for the two Roman colonies that were established there, Colonia Laus lulia Corinthiensis, established by Julius Caesar in 44 BC, and Colonia lulia Flavia Augusta Corinthiensis, established by Vespasian in the seventies AD. The urban grid of the Roman city of Corinth is largely the product of the Caesarian colony, and in addition there are two chronologically distinct, and geographically overlapping, rural systems of centuriation identified from the land that surrounds the city. It was common for a Roman colony to have under its control agricultural land outside the urban center, the territorium of the colony, and it was typically divided up in a regular manner to facilitate both the distribution of land to the colonists and the assessment of taxes from them.4 In Corinth, both the urban and the rural centuriation have been described based on the combination of topographical maps, satellite images, high- and low-level air photographs, and balloon photographs together with the electronic total station survey of above-ground architecture in and around the city.5
Much is known about the work of the Roman agrimensores from archaeological remains from different areas of Europe and North Africa. There also exist extensive literary accounts of the agrimensores, known collectively as the Corpus Agrimensorum Romanorum.6 The Corpus is a collection of ancient land surveyors' manuals originally compiled in the fifth century AD, but it includes texts that are as early as the first century AD. The surveyors' manuals give very specific information about the training of the agrimensores, their method of work, and the kinds of problems and issues they would have encountered during the course of their daily activities. There are also fragments of ancient stone maps from Orange (ancient Aurasio) that illustrate the Roman agricultural division of land-limitatio or centuriation.7 More commonly, perhaps, ancient maps depicting the work of the agrimensores would have been made on perishable materials that have not survived.
The agrimensores used as their principal surveying instrument the groma, a simple device, composed of a vertical staff with two horizontal crossbars, connected by a bracket. From each end of the cross-bars hung a cord, which was held vertical by a plumb bob (fig. 1). Roman surveyors were skilled at using the groma, together with sighting rods (decempeda), to create straight lines and right angles.8 The agrimensores sighted along the groma to the survey rods, hammered wooden stakes in the ground at every actus (see below), then drew a straight line on the ground connecting the stakes. Following this procedure, the surveyors created a furrow or a shallow ditch to represent the line.9 These furrows, or vestiges of these shallow ditches, have been found in various parts of the Roman world. In some places, vast areas of centuriated land have been recognized, for instance in the Po Valley of Italy or in portions of North Africa where hundreds of square kilometers of centuriated land are known.10 Elsewhere only fragments of organized land systems have been discovered. The urban planning of many Roman cities is noted for its organization and regularity, and the vestiges of this Roman planning with orthogonal plans are seen in such modern cities as London, Paris, Florence, and Barcelona.11
The Romans used as their primary unit of measurement the actus, or 120 linear Roman feet (1 Roman foot = 0. …