It is the military port founded by Augustus about 5 km. from Ravenna, which took its name from the fleet that provided for its allocation. The place where it is now Ravenna was once at sea, or, even in the ancient beach was advancing into the sea for deposits taken by the river Po and lying along the coast by sea currents. Therein was the most important port of call for the timber trade Alps. Ottaviano in the year 38. C. gathered a fleet and after the victory of Actium built a large military harbor for 250 warships, divided into 10 cohorts, and 10,000 sailors. This fleet (classis Ravennas or Ravennatium, or classis Praetoria Ravennas) was the army for the Adriatic and the eastern Mediterranean, and it was matched by that of the Misenus for the western Mediterranean. Augustus had to do the work to a channel, probably a branch of the river Po, called Padusa Messanicus and that he was called the pit of Augustus. It was 40 km long., And put in communication with the port and Ravenna marshes. From the classis Ravennas sailors who were posted in Rome were provided to the shows of naval battles, was detached from the fleet also the section of Aquileia, which probably became independent.
The city of Class was where now stands the basilica of S. Apollinaris in Classe. Between Class and Ravenna, and 3 km. by the latter, there was a town or village of "Caesarea" where the column is now called the "spreader", which reminds the church of S. Lorenzo in Caesarea destroyed.
Class A and Class sprang up around after the peace of Constantine, of cemeteries, the first sacred edifices of Ravenna, Class and was the residence of the bishops of Ravenna until the time when, having established the imperial court at Ravenna (402), also bishop's seat was moved. Ravenna and Classe formed an inseparable unit not only topographical, but also strategic. Around Class warlike operations took place and shook the great historical sieges for the occupation of Ravenna: Odoacer (476), Theodoric (491-493), Belisario (540). Class was stripped in about 579 Faroaldo by The Duke of Spoleto. Around 719 was invaded by Faroaldo II, but returned to Exarchate order Liutprando that attacked and destroyed himself some years later. It seems that the Lombards from hitting the city of class, but not churches or the interior or the suburbs. On the other hand class was riceduta by Liutprando, but did not escape, with Ravenna, new threats and invasions longobardiche. Lamb in sec. Class IX spoke of how the destructa Classis, the civitas Dudum Classis. But his fate was sealed by natural forces. The sliding motion of the waves and the current Adriatic coast, the abundant material conveyed by the floods and the changed water regime brimmed the harbor. It was the loneliness. Of many churches, including the oldest was the basilica of Probus, the first cathedral, the Basilica and the most grandiose Petriana, stood only the basilica of S. Apollinaris, Bishop Ursicino started and finished by Archbishop Maximian (549) with the aid of the Emperor Justinian. It is, with its columns and its marble, with its mosaic decoration, with the tombs of archbishops, one of the most famous monuments of Italy. Next to it there grew a monastery, illustrated by S. Romualdo, visited by Otto III, later owned by the Camaldolese monks. The remains of the old pier Classense were in sec. XV from Venice used for the foundations of the fortress Brancaleone, others were found in sec. XVII. And today still around for a 'wide area, the plow bites into the walls of buildings, lift blocks and tiles of mosaic floors, unearths inscriptions. The sea is 5 km away in a straight line., And the nearby pine forest expects to renew the dunes emerged.