Adjacent to the Old Town is an island on the Oder River – Ostrov Tumski aka Cathedral Island. This is the oldest part of the city, with structures here dating back to the 10-12th centuries. An island creates natural defenses so this was a natural place to develop. There are several noteworthy churches and cathedral here, including the magnificent Wrocław Cathedral, St Martin’s Church. Wrocław Seminary, Church of St Peter & Paul, Church of Our Lady of Sands, and other.