The Church of the Holy Saviour in Chora is considered to be one of the most beautiful surviving examples of a Byzantine church. In the 16th century, during the Ottoman era, the church was converted into a mosque and, finally, it became a museum in 1948. The interior of the building is covered with fine mosaics and frescoes. Name, Chora, referring to its location originally outside of the walls, became the shortened name of the church. The original church on this site was built in the early 5th century, and stood outside of the 4th century walls of Constantine the Great. However, when Theodosius II built his formidable land walls in 413–414, the church became incorporated within the city's defences, but retained the name Chora.