The Arab baths are a Romanesque building and were built in 1194 with a structure that imitated that of the Muslim baths. The siege of 1285 caused considerable damage to the building. In 1294, James II of Aragon ceded it to Ramón de Tolrà in exchange for its restoration. The establishment functioned as a bathhouse until it was closed in the 15th century. From then on, it passed into private hands, which put it to other uses. In 1617, a convent of Capuchin nuns was established and used it as a pantry, kitchen and laundry. It was during the 19th century that the term 'Arab Baths' became popular to refer to the building. In 1929, the baths became public property and were renovated.

The baths are divided into five rooms: the changing rooms, the cold room, the warm room, the hot room and the furnace and boiler room.

They are similar in plan to Roman baths, copied from North African Muslim models and with late Romanesque ornamentation.

The frigidarium has a central octagonal pool with a small dome over it. The roof is a half-barrel vault. It consists of a square room with a span of 10.8 m, in the centre of which is a regular octagonal base with an outer side of 1.52 m and a depth of 0.32 m lower than that of the room.

On this base, which is 0.90 m high, rest eight columns, one at each angle, with their corresponding arches that end in a domed octagonal dome. The temple is made of stone and its height from the pavement to the end of the dome is 12.2 metres. Above the vault is a sloping roof with the second section of the temple with the dome protruding from its centre, through which the room receives light, although light also comes in through windows on both sides of the vault. The capitals are decorated with foliage and animals, and the arches are semi-circular rather than horseshoe arches.

On the south wall of the nave there were three niches for storing bathers' clothes, and on the other walls there was a stone bench.

The tepidarium is a rectangular room covered by a barrel-vaulted ceiling with three rectangular lighting lanterns. It was the warm bath room.

The caldarium, the hot-steam room, is similar in structure to the previous one. The floor is over a hot-air room like the hypocaust of the Roman baths. The half-barrel vault has poly-lobed vents.

The next room, which is very deteriorated, is another caldarium.

The caldarium was excavated in the subsoil outside the building.