Located on a hill, almost on the border of the province of Zamora, and within viewing distance of Villalonso Castle, the primitive Tiedra Castle is already mentioned in the 11th century.
The present castle seems to date from the end of the 13th century and is in a bad state of conservation. It consists of a polygonal enclosure, with a perimeter of 115 meters, equipped with two circular towers. Near one of these there are remains of a ruined wall. This could be a vestige of a second defensive enclosure. There is a dry moat on its western side.
In the 13th century a Don Alonso Téllez de Meneses was the Lord of Tiedra. In the 14th century the Lord of Tiedra was Don Sancho, Count of Alburquerque and brother of King Enrique II de Trastamara. His daughter Leonor, Countess of Alburquerque and married with Fernando de Antequera, inherited from him, amongst other possessions, Tiedra Castle. His sons Enrique and Juan, the Infants of Aragon, inherited from their father the castles of Medina del Campo and Peñafiel Castle. Both the brothers fought against King Juan II of Castile. Therefore this king confiscated Tiedra Castle and handed it over to his favorite Don Alvaro de Luna. During these wars the king incarcerated several of his enemies in Tiedra Castle; under these prisoners were the Count of Haro, the Lords of Batres and Valdecorneja and the bishop of Palencia. After his defeat, in 1445, in the battle of Olmedo, the enemies of the king, handed the castle to Don Pedro Girón, Master of Calatrava as a reward for his help. This Don Pedro Girón is the same one who would, in later years, received Peñafiel Castle from King Enrique IV.
Until the 19th century the castle belonged to ducal house of Osuna.References:
The Petersberg Citadel is one of the largest extant early-modern citadels in Europe and covers the whole north-western part of the Erfurt city centre. It was built after 1665 on Petersberg hill and was in military use until 1963. It dates from a time when Erfurt was ruled by the Electors of Mainz and is a unique example of the European style of fortress construction. Beneath the citadel is an underground maze of passageways that can be visited on guided tours organised by Erfurt Tourist Office.
The citadel was originally built on the site of a medieval Benedictine Monastery and the earliest parts of the complex date from the 12th century. Erfurt has also been ruled by Sweden, Prussia, Napoleon, the German Empire, the Nazis, and post-World War II Soviet occupying forces, and it was part of the German Democratic Republic (East Germany). All of these regimes used Petersberg Citadel and had an influence on its development. The baroque fortress was in military use until 1963. Since German reunification in 1990, the citadel has undergone significant restoration and it is now open to the public as a historic site.