'View of the Bosphorus: The Castle of Europe', 1890. On the European shore of the Bosphorus, Rumelihisari medieval fortress was built between 1451-1452 on the orders of Ottoman Sultan Mehmed II in preparation for a planned Ottoman siege on the then-Byzantine city of Constantinople. From "Cassell's Illustrated Universal History, Vol. III - The Middle Ages", by Edmund Ollier. [Cassell and Company, Limited, London, Paris and Melbourne, 1890. ]