At point of intersection between the cardus maximus and decumanus maximus, in correspondence with the present Piazza Tre Martiri, was the Forum, the heart of public life and business transactions.
In the Forum, the archaeological findings visible in the spaces saved from the paving remind us that, in the age of Augustus, the paving in chalky stone covered the whole square, closed in on the North by the theatre in brickwork and on the Southern side by the archway which signalled its entry; the basilica, which was where legal and business activities were administrated in Roman times, rose on the side close to the sea, across from which is now via San Michelino in foro, and in the first block towards the north stood a theatre built in the time of Augustus. The scenario included honorary monuments, statues and inscriptions in memory of emperors and benefactors of the community. The remains of an imposing column in stone-cold marble and a large terracotta container belong to the theatre, today almost completely cancelled from the urban fabric.
The Forum is also dominated by the memory of Julius Caesar, evoked by two modern signs, the statue in bronze and the stone milestone at the head of via IV Novembre. According to tradition (but never confirmed in any report written by the general himself), he would harangue his army in the very forum of Ariminum following the passage of the Rubicon. And it is from this version of events that we learn about a huge stone which Caesar stood upon to address the troops, a stone which, up until the last war, was located on the milestone erected in 1555 in memory of the event.