The torresotto, or Porta Nova gate, belongs to the second ring of walls, the so-called Torresotti ring, completed in 1192. The ring was 4 Km long and included 16 gates and 2 posterns (small inconspicious doors). The walls were 8 m high and decorated with brick merlons (solid upright structures). Three rings of walls built over several centuries surrounded the whole city. The oldest ring, made of seleni- te (a common local stone) blocks, was made centuries earlier than the last one corresponding to the current inner ring road.