The Hıdırlık Tower
From the Wikipedia: The Hıdırlık Tower (Turkish: Hıdırlık Kulesi) is a landmark tower of tawny stone in Antalya, Turkey, where Kaleiçi meets Karaalioglu Park. It is believed that the ruling Roman Empire built this in the second century CE on a square plan. The same century, it was turned into circular tower.

It has since been used as a fortification or a lighthouse.

The tower is situated at the southern side of the place, where the land walls of the city join the sea walls. The 14 metres (46 ft) high structure consists a circular tower rising on a quadratic pedestal. The tower's gate at the eastern side leads to a small room, from where a narrow staircase goes up. There are signs of restoration work on the upper part done in the Seljuk and Ottoman eras.

From a folder by the city: "The reason for the tower’s construction is still subject to argument. Although it resembles Roman period mausoleums in plan, it more likely served as a lighthouse and watchtower for the harbour."