The Byzantine church of Panagia Gremiotissa dominates the Chora of Ios with its imposing architecture. The view from the spot is truly impressive. The church is built on the edge of the Venetian castle and is one of the most popular attractions on the island. It was built by the inhabitants of Ios in honour of the miraculous icon of Virgin Mary that was found in the area. It remains an unresolved mystery how the icon got there.