In the main body of the cathedral, the most noticeable features are the great boxlike choir loft, which fills the central portion of the nave, and the vast Gothic retablo of carved scenes from the life of Christ. This altarpiece was the lifetime work of a single craftsman, Pierre Dancart. The builders preserved some elements from the ancient mosque. The mosque's sahn, that is, the courtyard for ablutions for the faithful to conduct their ritual cleansing before entering the prayer hall is known today as the Patio de los Naranjos. It contains a fountain and orange trees. However, the most well known is its minaret, which was converted into a bell tower known as La Giralda, and is now the city's most well-known symbol. The Giralda is the bell tower of the Cathedral of Seville. Its height is and its square base is above sea level and long per side. The Giralda is the former minaret of the mosque that stood on the site under Muslim rule, and was built to resemble the minaret of the Koutoubia Mosque in Marrakech, Morocco. It was converted into a bell tower for the cathedral after the Reconquista, although the topmost section dates from the Renaissance. It was registered in 1987 as a World Heritage Site by UNESCO. The tower is 104.5 m in height and was one of the most important symbols in the medieval city. Construction began in 1184 under the direction of architect Ben Ahmad Baso. According to the chronicler Ibn Sahib al-Salah, the works were completed on 10 March 1198, with the placement of four gilt bronze balls in the top section of the tower. After a strong earthquake in 1365, the spheres were missing. In the 16th century the belfry was added by the architect Hernán Ruiz the Younger; the statue on its top, called "El Giraldillo", was installed in 1568 to represent the triumph of the Christian faith. Seville Cathedral has fifteen doors on its four facades. The major doors are:  The Door of Baptism, on the left side, was built in the 15th century and decorated with a scene depicting the baptism of Jesus, created by the workshop of Lorenzo Mercadante of Britain. It is of Gothic style with a pointed archivolt decorated with tracery. It contains sculptures of the brothers Saint Isidore and Saint Leander and the sisters Saints Justa and Rufina, by Lorenzo Mecadante, also a series of angels and prophets by the artisan Pedro Millán.