The cathedral is dedicated to St Thecla and is erected at the top of the acropolis or hill of the ancient city. Its construction began in the year 1171 and it was consecrated on 4 July 1331. Its foundations and later architectural development are located on the remains of an ancient Roman construction begun in the second quarter of the 1st century bc. and completed at the beginning of the Vespasian Empire (69-79 AD). The Cathedral is gothic in style. Its floor plan is in the form of a Latin cross, with three naves each with their own apses and transept. The head is of Romanesque tradition with half-point arches supporting the extension of the stone wall and pilasters following the new constructive techniques of the Gothic movement.