The tower of arms, or Homage tower, is the highest tower in the castle; it's circular and has an outer diameter of 6.10 m with an outer heigth of about 15 m.
This building, dating from 1316-1317, is among the lines of ramparts, and rests directly on the rock. It has an entrance made of stone, which features an interesting threshold construction; so you can see the door's anchoring and closing systems, in particular the four pieces with a hole for entering the axes about which a door of two sheets revolved. Inside the tower you can see their primitive inner composition into three sections, with the different brands of flats: two above the entrance's ground (with an internal diameter of 4 m), and an underground section (of 3 m internal diameter) and perhaps it was used as a dungeon, and nine loopholes with 1.20 m tall (that is, the long and narrow rectangular openings practiced on the wall in order the light to came into, and also to shoot arrows using bows or crossbows), and, above, looking upwards, the superb dome, that originally was covered totally.
Historical written sources record numerous restoration work in the tower. For example, in 1329, the machicolation, that is, the outside walking, or tower's parapet was added, and then in 1489 there was constructed the spherical dome, which replaced the previous cover a roof dating from 1452, "since it had fallen, was in great danger and great ruin", as the written sources recall. The dome and the wall were recently restored in 2011.
Also, many sources speak of a shield that would be located in the key of this dome, which would be the teaches of knight of count Nunyo Sans, who accompanied the King James I in the conquest of Majorca by the catalans in 1229, and who owned the castle until his death in 1241, when the castle came to royal hands. It is believed that, originally, the top floor would be for the castle's watcher, or its responsible, as it could be connect, through an access, with the parapet or the guard pass of the walls to which is attached.
The exterior is very similar to the Vatican's Leonina tower (of the 8'th century) in Rome, and served as a model in the towers built in XVI century in Felanitx between the castle and the coast.
The oral tradition tells that around 1459, remained locked in the castle, and particularly inhabited this tower, Prince Charles of Viana, son of King John II of Navarra, and brother of King Ferdinand of Aragon, the Catholic, which was banished to Mallorca by his father. From this tradition and supporting documents, some defend the hypothesis that Prince Charles of Viana fathered Christopher Columbus, the America's discoverer, as result of a relationship with a young woman of Felanitx, named Margalida Colom.