Its origins date back to 1158, when building work began. In the 14th and 16th centuries it underwent various modifications until it attained its current appearance. It has three naves with a transept, ambulatory, triforium and an ogival vaulted ceiling. Outside, special mention should be made of the Romanesque apse, Baroque tower and South or 'Santo' entrance, with a semi-circular arch, images set in niches and circular skylights. The main altarpiece is in alabaster and walnut and was completed in 1545. There is some outstanding 16th-century Plateresque ornamentation on the choir stalls. Amongst the different chapels, special mention should be made of El Sepulcro de Santo Domingo (with recumbent statue); Santa Teresa (pantheon of the Marquises of Ciriñuela); La Magdalena (one of the most richly appointed in the cathedral); El Santo Cristo (with two altarpieces, one Renaissance, the other Baroque); San Pedro (which conserves part of its Romanesque structure). The cloister dates from the 14th century, although it was later modified in the 16th. The sacristy and chapterhouse are home to important works of art, such as several Hispano-Flemish triptychs from the 15th and 16th centuries, and a range of precious metalwork.