In the 3rd Century A.D., the Roman Empire’s control of the Rhine was slowly but surely well into its decline. The Limes fortification and defense system, extending from the southern and eastern parts of the country northwesterly to the eastern banks of the Rhine, was already seriously threatened by German tribes.Close to the Roman-Germanic Central Museum stands a replica of the arch built in 1962, while the original resides safely in the Landesmuseum. Located above the arch’s frieze displaying the symbols of the zodiac, sit the ancient reigning gods of antiquity, Jupiter and Juno, enthroned in the center. Later, as the Germanic incursions became an increasing threat even for Moguntiacum, a new city wall was erected in the middle of the 4th Century.