Lower register
The Ara Pacis, composed of a fence that encloses the altar proper, reproduces the forms of a templum minus, as described by Festus: "I templa minora" are created by the Augurs (priests) by fencing off the chosen places with wooden boards or cloths, so that they have no more than one entrance, and delimiting the space with established formulas. So the temple is the place that is fenced in and consecrated so that it remains open on one side and has corners firmly fixed to the ground”.
If one makes exception for the entrances, which in the case of the Ara Pacis are two, this description fits particularly well to this monument and its decoration which, in its lower part, represents the wooden planking that, in archaic temples, delimited the space 'inaugurated' with sacred formulas.