The Giants' grave of Su Mont'e s'Abe is an archaeological site located in the municipality of Olbia. Like other giants' tombs of Gallura, it was built in two main phases of construction. In the first stage, during the period of the Bonnanaro culture, it was built an allée couverte tomb; later, in the second phase, during the age Nuragic age (1600 BC approximately), the allée couverte was transformed into a giants' tomb with the realization of the exedra and the erection of the central stele of which few traces remain today.
The tomb, which measures about 28 meters in length and six in width, was excavated and restored in the 1960s.
References:Château de Niort is a medieval castle in the French town of Niort. It consists of two square towers, linked by a 15th-century building and dominates the Sèvre Niortaise valley.
The two donjons are the only remaining part of the castle. The castle was started by Henry II Plantagenet in the 12th century and completed by Richard the Lionheart. It was defended by a rectangular curtain wall and was damaged during the Wars of Religion. In the 18th century, the castle served as a prison.
The present keeps were the central point of a massive fortress. The southern keep is 28m tall, reinforced with turrets. The northern tower is slightly shorter at 23m. Both are flanked with circular turrets at the corners as well as semicircular buttresses. Each of the towers has a spiral staircase serving the upper floors. The Romanesque architecture is of a high quality with the dressed stones closely jointed.