The busiest Poreč street is called Decumanus. In Roman city planning, a decumanus was an east-west-oriented road. The main decumanus was the Decumanus Maximus.
In the middle, or groma, the Decumanus Maximus crosses the perpendicular Cardo Maximus, the primary north-south road that was the usual main street. The Forum, ie. the public square for trades and meetings, is normally located close to this intersection of the Decumanus Maximus and the Cardo Maximus, and such is the layout found in Poreč.