Decumanus Maximus

Decumanus is a term from the Roman land surveying. It refers to the vertical line in a right angle measuring system applied.

Originally the term was used in cosmology and called the East-West axis, which was used as a line of sight with the observation of celestial motion. The counterpoint is the cardo -called North-South axis. The decumanus divided the sky into a day and a half of the night, the cardo, however, in a sunrise and a sunset half.

In the gromatischen practice, put on a decumanus maximus (DM ), a main orientation axis, which did not follow astronomical, but topographical aspects. Most of the decumanus was created there, where the maximum extent of a city to be applied was possible, or where there was already an existing road. The orthogonally to the standing axis was the cardo maximus (CM). On these two main streets they took as the creation of new cities. With the groma mentioned survey instrument, a coordinate system was created, which served as the basis for further and parcels to be created streets of the city. The decumanus maximus was applied in a width of 40 Roman feet ( 12 meters). The always corresponded to twice the width of the cardo maximus.

The decumanus was also applied in the construction of military camps and as prorsi ( " face the enemy" ) referred.