Centuriation In The Po Valley. The modern road and field system in this air photograph taken in 1945 clearly reveals its origins in
the Roman land-divisions of the second century B.C. Large squares with sides of 20 actus (2,400 Roman feet = 710 metres) and an
area of 200 jugera are subdivided into narrow strip-fields.
The Roman conquest of Italy was also accompanied by a striking physical expression of the fact of a Roman presence. Prior to its
distribution, whether as isolated lots or in the territory of a colonia, conquered land was at any rate from the late fourth century
onwards measured and marked out by an elaborate process eventually known as centuriatio. Initially, perhaps from 334 onwards,
land was divided into strips 10 actus wide (1 actus = c. 35.5 m.); the lines of division were known as decutnani. In due course a full
rectangular grid was marked out; the transverse lines of division were known as kardines. Just as in the simpler system the
decutnani were sometimes more or less than 10 actus apart, so in the developed system a grid of 20 x 20 actus was the norm, but
not universal. When such a grid was used, the result was 200 jugera, or a centuria, within each square.
But this elaborate process was not used merely for measuring the land; the lines of the grid were marked out by roads and ditches
which left an indelible mark on the countryside; they patterned and structured its use for centuries, if not millennia, and survive in
many areas to this day, despite industrial development and mechanized farming.