The Triumphal Arch is the most recognisable monument at Volubilis and one of the best-preserved Roman arches in North Africa. It stands at the northern end of the Decumanus Maximus, the city's main street, and was built in 217 AD to honour Emperor Caracalla. The arch is decorated with niches that once held bronze statues, and the flanking columns still carry elaborate carved capitals.
Seen from the Decumanus, with the Atlas Mountains visible in the distance on clear days, the arch frames a view that has barely changed since Roman times. The road in front of it, still paved with the original stone blocks worn smooth by centuries of cart traffic, stretches the full length of the plateau past the columns of the Forum and the facades of the great merchant houses. It is the single most atmospheric spot in the site and worth lingering at both early in the morning and again near sunset.
Sources: - https://en.wikipedia.org/wiki/Volubilis