Terena Castle is located in the south-east of Portugal, in the village of Terena. The medieval castle was supposedly built in the 13th century. Historical documents indicate that in 1262, King Afonso III granted Teren to his knight Gilles Martins. It is believed that at this time, in order to create fortifications on the border with Spain, which passed along the Guadiana River, the construction of the castle was started. It is also known that in 1380, during the reign of Fernando I, a barbican was built to further protect the entrance to the castle. In the 15th century, King Juan I donated personal funds to the Avis Order to reconstruct and strengthen the castle’s defenses. In 1482, Juan II appointed Nuna Martins da Silveira the Alcald of Terena, he was ordered to continue work to strengthen the castle. Fortification work was actively carried out in the first decades of the 16th century, under King Manuel I, at that time a donjon and an Alcalde palace were built. The castle has the shape of an irregular pentagon, with four round towers arranged asymmetrically. The walls and castle structures are made of granite, marble, quartz and slate. On the sides of the main gate, for their additional protection, two towers were built. Opposite the main gate, on the eastern side of the fortress wall, are the so-called "Gate of the Sun." The 15-meter dungeon has a quadrangular shape, inside it is divided into two floors, the upper terrace of the tower is equipped with battlements with loopholes. In 1652, during the Portuguese war with Spain, the castle was captured and plundered by the Castilian army. In the future, it was decided not to reconstruct the castle of Teren, but to direct all efforts to the construction of defensive structures in the city of Elvas. As a result of the earthquake of 1755, the castle was badly destroyed. The first reconstruction of the castle was initiated by the Directorate General for National Buildings and Monuments. In 1937, the exterior wall was repaired and its teeth restored. In 1946, the castle of Teren was included in the register of national monuments of Portugal. Since 2000, an annual festival has been held in the castle under the auspices of the international association Inter-Medieval with the reconstruction of the medieval knightly tournament.