The arch stands near the Piazza del Mercato (Market Square), which was once the Forum. Based on inscriptions still visible on the arch, it dates back to 23 AD and was built by decree of the Senate in honor of Drusus, son of the emperor Tiberius, and of Germanicus, cousin of Drusus but who became his brother after being adopted by Tiberius. It is formed by a single arch made from large square blocks of stone carved on the front to form a decorative frame; only fragments of it survive today. During the Middle Ages it was incorporated by neighboring buildings and, only thanks to renovations in the 1950s, today it is possible to admire the eastern part of the structure visible down to the ancient base.