In the, 4th century Aix, now a free city of the Holy Roman Empire, played a conspicuous part, especially in the league which, between 1351 and 1387, kept the peace between the Meuse and the Rhine.
The momentary effect was immense; for some of the halo of the Holy Empire still clung round the head of the house of Habsburg, and Francis Joseph was welcomed to the ancient free city with enthusiasm.
The latter, however, made it the base of his operations against the Romans in 89, 72 and 67 B.C. Pompey made it a free city in 65, after Mithradates' fall.
Zara became a free city under Italian sovereignty, but as a tiny isthmus without hinterland or islands.
Charlemagne, who had a palace in the neighbourhood, gave privileges to Mainz, which rose rapidly in wealth and importance, becoming a free city in 118.