The Torre del Fraile is one of a set of military watchtowers built around the South and East coast of Spain to keep an eye on passing shipping and Barbary pirates. The watchtowers were in sight of one another and it was therefore possible to get a signal to Gibraltar from the watchtower in Tarifa. The tower was designed by Luis Bravo and Juan Pedro Laguna in 1588.
The tower is about 240 metres back from the sea and Cala Arenas and 120 metres above it. The tower is over six metres in diameter and was over thirteen metres high until the top collapsed in 2006 with the loss of a window and the upper staircase. The tower's entrance was over five metres in the air and this led onto a floor. From this the soldiers could climb to the top where space was reserved for firewood for signalling.
References:Sigmaringen Castle was first mentioned in the year 1077 in the chronicles of Petershausen monastery. The oldest parts of the castle are concealed beneath the alterations made during the 17th and the 19th centuries. The secret of the earliest settlement built on this defendable rock will never be fully revealed: large-scale excavation work would be necessary, which the extensive land development renders impossible. Judging from the many Roman remains unearthed in the area around Sigmaringen, the 12th century keep known as the 'Roman Tower' could be traced back to a Roman predecessor.
The castle remains that have been preserved (gate, great hall and keep) date back to the Staufer period around 1200. The castle remains were integrated into subsequent buildings. The foundations of the castle buildings are to a large extent identical to the surrounding castle wall.
These remains give us a good idea of how the castle might have looked during the 12th century.