Descripción: Walled Towns Friendship Circle.
«The Walls are undoubtedly one of the country's most outstanding monuments of the Roman era; the entire ancient outline has been preserved, despite mediaeval and modern rebuilding.
They were built between 260 and 310 AD. They are 2.140 metres in thickness between 8 and 12 metres in height. The walk along the walls - the adarve - is wholly passable, and is between 4.5 and 7 metres wide.»