This striking five-storey octagonal defence tower, measuring nearly 30m in diameter, more than 30m in height and with a central cistern within for water storage, looms over the harbour at the lower end of Ä°skele Caddesi. Constructed in 1226 by Seljuk sultan Alaeddin Keykubad I (who also built Alanya Castle), it was the first structure erected after the Armenian-controlled town surrendered to the sultan, and is now the city's symbol. Climb the 70-odd steps to the roof; the views are amazing.