The Romans were also specialist brick makers as can be seen here. The arches are built everywhere and I guess it was a very easy and strong way to build walls and roofs as it was all self supporting but it still amazes us how they worked out such intricate building techniques and the ability to make bricks and mortar that has lasted thousands of years. This all was done in quite a harsh environment as you can see as there is little shelter from trees and the area is nearly solid rock and quite inhospitable. The columns are the original entrance to shops on the lower floor with the upper level being the Temple of Domitian one of the Roman Emprors.