In the 2nd century B.C., a great wall was built around Tarraco, delimiting the municipal boundaries. The wall originally ran some 3500 metres. Today, approximately 1100 metres remain, bordering present day Tarragona’s Old Quarter. The most interesting portion of the surviving wall is to be found along the Passeig Arqueològic, or Archaeological Promenade. There, several perfectly conserved sections can still be seen, revealing the unusual megalithic foundations, as well as two of the original six posterns and a larger gate that was used for vehicular traffic. Of the three surviving bastions, special attention should be paid to the Archbishop’s Tower, which underwent considerable alterations in the Middle Ages, and the Minerva Tower, which is the site of the oldest Roman sculpture and inscription in the Iberian Peninsula.