Monastery of San Juan de Duero, built in the Romanesque style, consists of a single nave with a wooden roof, semicircular apse, and a pointed barrel vault. From the 12th century it belonged to the Knights Hospitaller of Jerusalem, until it was abandoned in the 18th century. The 12th century church and the 13th cloister, with Gothic and Mudéjar elements, are still standing.The arcades combine the various architectural styles current in Spain at the time: late Romanesque, early Gothic, and especially, Islamic tracery. These arches are criss-crossed to achieve a beautiful visual effect. Inside the church there is a display of items from Jewish, Islamic and Christian cultures.
References:The Cathedral of Saint Mary Major, often called Lisbon Cathedral or simply the Sé, is a Roman Catholic cathedral located in Lisbon, Portugal. The oldest church in the city, it is the seat of the Patriarchate of Lisbon. The cathedral has survived many earthquakes and has been modified, renovated and restored several times. It is nowadays a mix of different architectural styles.
The site where it stands was the principal mosque of Lisbon when it was an Arab settlement. The construction of the cathedral started around 1150, three years after the city was conquered from the Moors during the Second Crusade. Shortly after the victory the English knight Gilbert of Hastings was named bishop of the city of Lisbon.
One good reason to visit the Cathedral is to visit its charming cloisters located in the back. There are several tombs in the cathedral, the most notable of which is the beautifully sculpted tomb of Lopo Fernandes Pacheco and his wife.