The present building represents the old possessió houses of the Son Mas farmstead. The first existing documentation on the occupation of the hill where they lie comes from the archaeological remains found in the early 90s. They provide clues to a group of huts and building structures from the Talayotic era. A large amount of Roman remains were also found, which indicates the existence of a Roman villa or fortification.
There is evidence of this property in the documents of the Repartiment of the island in 1232, when the Bishop of Barcelona transferred the farmsteads of Cornuatera and Buendar to Robert Seriol. The Seriols owned the farm until 1435, which then went to the Pomars. In the 15th century, the property fell into the hands of Jaumeta Pasqual, who married Guillem Desmas. In the early 16th century, with the settlement of the Desmàs family, the farmstead changed its name to Son Mas.
The fateful day of 2 August 1578 marked one of the most deep-rooted events in local popular tradition, which consisted of a Berber attack on the village defended by the honourable Rafael Juan of Son Corso. The Son Mas possessió was also attacked and defended by the nanny of Captain Guillem Desmàs. She managed to wound two attackers who were subsequently buried under a carob tree in said possessió, known as “the Garrover of the Moor”.
In 1716, Francesc Desmàs Buils, son of a woman of modest social roots, could not inherit the possessió and so it went to their relatives, the Marquis de la Torre, from the Truiols family. They were the landlords of Son Mas and Son Vida well into the 20th century. In the early 20th century, the Marquis de la Torre sold Son Mas to the iron and steel businessman, Antoni Mulet i Ferragut, who changed the possessió houses into a Neo-Gothic palace with a medieval appearance. He followed the historicist trends of the time, improving the farm estate and turning the driveway in a wide street.
The current building, protected as a site of Cultural Interest, has a built surface area of 3,600 square metres. In 1998, once acquired by the City Council of Andratx, it underwent a full refurbishment in order to house the municipal offices. All of the walls and perimeter sections were topped with battlements and small towers so as to make it all uniform. This layout continued on the portal forà (main entrance) with a semi-circular arch overlooking the monumental entrance located among the small towers.
The volumetry of the castle complex consists of a three-storey U-shaped structure, surrounding a courtyard built as a typical clastra. Attached at the far south-west is a defensive tower with a square base, which dates back to the late 15th century, known as the Torre des Sagrament. Until 1996, in the middle of the clastra, there was a water tank, which today can be found in the garden of the west wing. In the defence tower, three different styles of windows can be observed along a central axis, with emphasis on the pointed and horseshoe windows. The main entrance leads to the aforementioned clastra overlooking a grand staircase decorated with Gothic-inspired cloisters. It leads in to an exchange formed by Gothic arches overlooking the main floor. The remaining composition focuses on three styles according to the floor, with emphasis on the Gothic windows and the decorative plant and zoomorphic elements.