added by archaeologs
Term for the main north -south axis of Roman towns and military forts and camps. Technical use of the term seems to originate with Roman agricultural surveying practice, where cardo denotes the principal north-south axis of the site, about which other measurements 'hinge'. In a typical process of centuriation (division into a hundred parts), the cardo is used with the other principal axis, the decumanus (properly due east-west) to divide a given area up into squares (reckoned to be 2400 Roman feet square), each of which is subsequently to be divided into one hundred smallholdings. It is likely that this agricultural technique underlies what from the 4th century BC onwards became the characteristic Roman grid system that Roman planners gave to so many army camps and new towns. For the technique itself, it is likely that the Romans were indebted to the Etruscans (though probably not so slavishly as Roman writers would themselves suggest) and to the Greeks, both of whom seem to have used grid town-planning, but almost exclusively only for colonial rapid expansion. The cardo need not be precisely aligned northsouth, nor the decumanus east-west; what matters for the grid is the right-angle contained, and the subdivision into squares. The actual superimposition of the grid upon the terrain might be varied for all kinds of reasons, some perhaps religious, and some practical, such as the natural fall of the ground. The convention of referring to these urban axes as cardo maximus and decumanus maximus does not have direct classical authority.
The Macmillan dictionary of archaeology, Ruth D. Whitehouse, 1983
The term for the second major road of a Roman town, fort, or camp -- the main north-south axis. The term seems to originate with Roman agricultural surveying practice, where cardo denotes the principal north-south axis of the site, about which other measurements 'hinge'. When a site is divided, the cardo is used with the other principal axis, the decumanus (east-west) to sectioned into squares. From the 4th century BC, this system was adopted for the Roman grid system used for army camps and new towns. The technique was taken from the Etruscans and the Greeks, both of whom used grid town-planning. The cardo maximus was the main north-south road.