The pride of Alba is its walls, nearly two miles of them, surrounding the three hills on which the colony lies. The material is limestone, which breaks at the quarry into irregular, polygonal blocks. These are set without mortar. The excavators distinguished four different building techniques in the wall. They assumed that the roughest sectors, built of enormous blocks, were the oldest, coeval with the foundation of the colony. These polygonal walls, common all over central Italy, used to be called Pelasgian or Cyclopean, and were formerly assumed to be of immemorial antiquity, but recent archaeological work has pushed the dates of most of them down into the late fourth century or later. At Alba the techniques involve the use of smaller blocks and more careful workmanship in successive phases, until finally with the use of cement we reach the 80’s B.C. and the age of Sulla. On the northwest, where the hill has the gentlest slope, the circuit is triple, and the outermost is the latest. The loop to the north was the _arx_; it was destroyed by an earthquake in 1915. The wall is pierced by four gates, some with portcullis and bastions. The Via Valeria entered at the northwest, made a right-angled turn, passed the civic center, and emerged at the southeast; that is, it was made to conform to a grid plan within the colony, a grid plan laid down despite the hilly terrain, which made terracing necessary. Excavating Alba’s civic center, the Belgians found a Forum, with altar and miniature temple, buried under many feet of earth. They also found a basilica (a rectangular roofed hall with nave and two side aisles, used as a law court and commercial center), presenting its long side, with three entrances, to a portico facing the Forum. Beside the basilica, a market, with baths on one side and a temple on the other, with early revetments, repeatedly restored. An adjoining street, parallel to the Valeria, was lined with shops, including a fuller’s drycleaning establishment and at least one wine shop. The doorsills still show slots for the shutters. In front of the shops ran a portico supported on high pilasters. In the curb were holes where customers might tie their mules. At the corner of the _decumanus_, the excavators found charming statuettes of elephants, used as street signs. Under the market were revealed subterranean chambers accessible only by manholes; the excavators suggest that these are the very dungeons, dark underground _oubliettes_, where prisoners of state like King Syphax of Numidia in 203 B.C., King Perseus of Macedonia in 167, the Gallic chief Bituitus in 121 were incarcerated, for the Romans often used their colonies as detention points.