The Tower of the port of Bosa, located in Bosa Marina, also known as the Tower of the Red Island, was probably built in the middle of the 16th century, and is mentioned for the first time in 1572 (Report Camos) and already restored in 1579.
Above the entrance is still visible the weapon, four vertical posts, belonging to the Villamarì, lords of the town until 1556.
Considered one of the largest in Sardinia, it was used for heavy defence and was manned by an Alcaid, a gunner and six soldiers. Antonio Ruyz, is the first Alcaid or governor of a fortress according to the documented Spanish tradition of the Bosan tower.
As well as defending against the barbarians, it also served as a prison, customs, health and harbour guard. The interior, which was accessed via a wooden staircase, was partitioned for the rooms and had a large fireplace. It still has numerous Catalan-Aragonese decorative elements in red trachyte and the domed vault with large ribs and central pillar.
The tower is in close visual connection with the Tower of Columbargia to the south and the Argentina Tower to the north.