The streets names in roman planning derive from the names given to streets within a roman military camp. A street running from east to west was referred to as the decumanus because in roman legionary camps such a street would pass between the tents of the 10th cohort (decimana) and the 9th cohort. Streets that ran at right angles to the decumanus were named Cardo. The main street that connected the east and west gates had the addition of “Maximus” to indicate its significance.
In Gadara, the decumanus maximus follows a route from the Abila gate in the east, curves around the original settlement hill and then runs straight west for over 1.5km.
As the city developed in several phases of urban expansion from east to west, the first section of the street is much earlier and was first paved at some point in the mid 1st Century CE.
The decumanus maximus is paved with rectangular slabs quarried from the local grey basalt and laid at 45 degrees to the orientation of the street to stop cart wheels getting stuck in the gaps between slabs. However, roman aesthetic principles for architecture and planning promote regular perpendicular lines and rectilinear patterns. Therefore, to present a more aesthetically pleasing appearance in front of several high status buildings the slabs run parallel to the street rather than at 45 degrees.
Despite the hard wearing basalt paving, hundreds of years of cart traffic is evident from the ruts worn in the stone. These are more easily seen at the east end of the decumanus near the Nymphaeum where the paving is oldest.
As the city expanded westward during the late second and early third centuries CE, the paved decumanus maximus was also expanded westward and enhanced with the addition of colonnades along each side reflecting the increased prosperity of late roman Gadara.