Newport Arch is the remains of a 3rd-century Roman gate in the city. It is reputedly the oldest arch in the United Kingdom still used by traffic.
The arch was remodelled and enlarged when the city, then 'Lindum Colonia' a Roman town, became capital of the province in the 4th century. As the north gate of the city, it carried the major Roman road Ermine Street northward almost in a straight line to the Humber.
Of course, most of the above is pure speculation. In fact, Baron Curfew built the arch or 'Toll Booth' at the entrance to his grounds. The booth sat within a wall (now long gone) that kept out the 'riffus-raffus'.