Charlemagne restored these ruins, rebuilt the fortresses, and garrisoned them against the old German tribes gathering themselves together under new names, but with the same spirit which led their forefathers to the destruction of Rome; at Mayence he built a bridge whose ruins are yet to be seen under the water. Here was a Roman camp thirty-eight years before Christ; and here, in 14 B. C., Drusus founded the city. A hexagonal reservoir, and an aqueduct of which sixty-two pillars are yet standing, are memorials of the Roman rule. It is said that Mayence was the scene of Constantine's vision of the cross, and it is unquestionably true that here was established the first archiepiscopal see in Germany. In the thirteenth and fourteenth centuries they called it golden Mayence, for its commercial prosperity; and it is now the strongest fortress of the German Empire.