Mesa Kastro and Exo Kastro, respectively inner and outer castle, at Horio offer fine examples of Aegean defensive architecture. The Church of Christos, the oldest on the island, was built in 1592 by the priest Ioannis Ramfos. The 15th-century icon of the Panayia created by the Paleologoses in the church of Panayia Odigitria, the island's cathedral. The church of Ayios Ioannis Chrysostomos is an architectural gem of great historical and archaeological importance. It houses an 18th-century icon of Ayios Chrysostomos. The Kimolos Museum boasts a fine collection of pots dating from the Geometric and Archaic eras. Walking tours taking in a number of churches and chapels whose architecture is in perfect harmony with their setting.