This fortress, whose origins coincide with those of the city itself, dates back to the Moorish period, when it defended the north-south road towards Seville and reinforced the line of defence of the so-called Cora de Firrish, although there is evidence to suggest that it is based on the remains of an earlier Roman castrum and possibly other military structures that were built to take advantage of the dominance that the hill on which it is located has over the Osa Valley.
As it stands today, the Castle of Constantina consists of a polygonal enclosure of about ninety metres in diameter, which has an external defence in the form of a barbican, of which there are sufficient remains to affirm that it completely surrounded the enclosure. Most of this area has been preserved, and two of the seven towers that flanked it are still complete, containing magnificently built circular vaulted chambers (renovated in 2012).
The complex is arranged around a large parade ground and a large half-buried cistern, which ensured the water supply to the military garrison and is still in very good condition. The entrance was angled and protected by the twelve-metre high keep. It consisted of two floors and a roof that must have had larger battlements than the others and that controlled the population at the foot of the hill. The Castle was declared an Asset of Cultural Interest in 1985 under Act 16/1985 on Spanish Historical Heritage.
The solidity and austerity of the work and the harmony of the ensemble of this fortified enclosure, along with the marvellous views of the surrounding town, make this monument a place not to be missed.
The Sacred Heart Monument was built as a diocesan work in 1954, the promoter of the work being the parish priest of the town, Father Felix. It is strategically located next to the castle and, due to its height coupled with that of the construction itself (total height of of the monument 16 metres, height of the image 5 metres), the figure of Christ blessing the people completely dominates the town. Under the monument there is a small chapel where masses were once held to venerate the image.