The castle was originally built in the nineteenth century when Baron Sydney Sonnino decided to make his home there. The castle was built on top of a sixteenth century Medici building which itself had been constructed on an ancient fort that had been part of the coastal defence system centuries before. The pre-existing structure (a square tower known as San Salvatore Tower) was enlarged and raised. The manor house was completed with the addition an external chapel in 1895 which can still be visited today in the surrounding gardens. Sonnino, who had quite a high profile in Italian politics, loved his Livornese home. He was a severe and gruff man who was fascinated by the rough beauty and solitude of this part of the coast, an area he could survey from up high in his castle. He even made the decision to be buried here.
Today, the castle is a private residence and is not open to the public except for during special occasions such as the ‘Giornate del FAI’ in 2007. The property includes a mini port capable of docking ten small boats.
Sonnino Castle was built in neo-medieval style and the whole structure is covered with small battlements that make the castle look much more imposing when seen from afar. The interior is simple and austere. It’s still possible to identify the original Medici betterment, the interior of which is used as a large reception room today. The external chapel was also built in neo-medieval style.