The Elephant's tower is to the left and that of St. Pancras is to the right. 
Beginning in 1217, the Pisans settled in Cagliari concentrating themselves on the hill on which the neighbourhood of Castello is presently situated.  The stronghold was fortified with the construction of towers and walls.  This fortification's two most impressive towers remain today: the St. Pancras' tower on the north side of the castle and the Elephant's tower on its west side.  These represent one of Italy's best examples of medieval military architecture.
According to the inscriptions found on the two entrances, the le due torri were built by the architect Giovanni Capula in 1305 (St. Pancras) and in 1307 (Elephant).  They were built on an "L" plan with one open side and calcareous blocks and reach a height of about 30 meters.  Their interior has four wooden suspended ceilings that were added during their nineteenth-Century restoration.
St. Pancras' tower of  gets its name from its proximity to the small, homonymous church that rises along Buoncammino Way.  It was traditionally known as the Lion's tower because a lion was sculpted on its walls.  The Elephant's tower owes its name to the marble statue of an elephant, placed 10 m high to the left of the entrance.  The animal perhaps symbolically represents the tower's solidity.
Originally, the two towers served as lookout points over the sea and towards the island's interior.  Beginning with the Spanish domination and up until the first half of the nineteenth-Century, they served as prisons and torture rooms.  Capital punishment was carried out in the little square close to the Elephant's tower.  A tale is told that on very windy nights, the moaning souls of those executed in the small square can still be heard.
A third tower, the so-called Eagle's tower and twin of the others, controlled the southern side of the castle overlooking the sea.  Unfortunately, the English and Spanish naval attacks in the early eighteenth-Century and that of the French in 1793 almost completely destroyed it.  In 1840, the tower's ruins were incorporated in the construction of Boyl Palace, behind the Bastione di S.Remy.
The two remaining towers have undergone lengthy restoration and after several years, today can also be visited on the inside.