This church is dedicated to the Assumption and it is considered to be the most important Byzantine monument of Santorini. It was probably founded by Byzantine Emperor Alexios I Komnenos (1081-1118) and it must have been a Catholic monastery. According to written proof, the church was built in 1115. It was attacked by raiders and conquerors and belonged to the Orthodox for about 90 years. In 1207 the Catholic Franks conquered it and in 1537 (Turkish occupation) it belonged to the locals again. In 1860 the church became the headquarters of the diocese.
The first church that was built in this location was an aisled basilica which was eventually destroyed. The new church was built with parts from the old church or parts that were transferred here from ancient Thira. Also, there are two chapels nearby which were built much later.
The marble iconostasis of the church dates back to the 11th century. Also, the original church was decorated with frescoes, but they were all covered with mortar during the Turkish rule. Some of them were cleaned and uncovered so you can still see them nowadays in the north and the south chapel and on the roofs of the arches. The main themes are Saints, scenes from the New Testament, the life of Christ, Virgin Mary, etc.
