Castello al Mare (Castle by the Sea), Palermo

The Castle by the Sea (Castello a Mare) is situated in the Castellammare Archaeological Park, near the Cala, just north of the port of Palermo. Known historically as a crucial defensive bulwark for the port of Palermo, its significance spanned until the twentieth century. The initial fortification was constructed during the Arab era around the ninth century, strategically positioned to control and defend the port, close to La Cala, in an area adjacent to the Kalsa.

The present structure of the Castle by the Sea was established in Norman times by Robert Guiscard and the Great Count Roger following their conquest of the region. Until 1337, it served as the preferred residence of King Frederick III of Sicily, who personally reformed the prison system housed within the castle. Additionally, it functioned as a temporary residence for the viceroys of Sicily. During the Bourbon era, the castle was primarily used as a defensive structure and was notable for its role in anti-Bourbon uprisings in 1718 and 1734.

The castle functioned as a military barracks until 1922, then started being demolished as part of urban renewal efforts led by engineer Felice Giarrusso. Originally, it featured a quadrangular wall with the sea on two sides, encompassing a complex that evolved to include an Arab tower, Norman sections, 15th-century bastions, a Renaissance palace, and a 16th-century church, among other structures.

In 2009, following excavation and restoration works initiated in 2006, the remains of Castle by the Sea were brought to light, eliminating various post-war shacks and precarious dwellings. This marked the establishment of the Castellammare Archaeological Park. Future projects in collaboration with the Port Authority aim to flood some areas towards the current arrival of hydrofoils.

Today, remnants of the ancient buildings include parts of the main tower, the cylindrical tower, and the entrance body known as the "Aragonese gate". These ruins reflect the historical and architectural significance of the Castle by the Sea, preserving its legacy as a pivotal defensive and residential structure in Palermo's history.