The doors of Forlì The first city walls of Forlì were built in the early Middle Ages and today are difficult to recognize. It is assumed that it extended to defend the current Borgo Schiavonia, leaving the Abbey of San Mercuriale outside the city. The development of the city and the importance assumed by Forlì from the 12th century onwards made it clear that a new defensive wall was needed, and in the new expansion carried out in 1100, the Abbey of San Mercuriale was included and four access gates were built. In the late Middle Ages several gates disappeared, such as Porta Merlonia (in the middle of Corso Diaz), Porta Santa Chiara (on Via Dandolo). During the Middle Ages other gates were opened and closed, for example Porta Valeriana or Liviense (at the end of via Battuti Verdi) that, through a bridge no longer existing, connected the city to the countryside of San Varano. The Porta della Rotta in via Palazzola was also a vestige of the most ancient late Roman walls. The "four gates" system was crystallized with Pino III Ordelaffi and Caterina Sforza, erecting the last four gates known to us: Porta Cotogni (at the beginning of Corso della Repubblica), Porta Ravaldino (at the beginning of Corso Diaz), Porta San Pietro (at the beginning of Corso Mazzini) and Porta Schiavonia (at the beginning of Corso Garibaldi), the only one surviving.
