During your stroll through the old city of İstanbul you will come across allot of Sun clocks. They are mostly mounted on the walls of the mosques, meddresses (schools) or historical buildings.
Some unfortunately have been ruined and do not work but most of them have lived up to our time and work perfectly. I especially like to document them and watch them as the sun moves through the hemisphere. Nearly all the sun clocks are not easily noticed you need to be aware of what you are looking at.
You need to check the walls of the mosques where you see an Ottoman inscription with a metal pointer sticking out. This most probably will be a sun clock. The inscription is in ottoman as most of them have been built during the reign of the empire. These clocks have been used as watches to show the time of prayers for the believers.
So if you are aware and attentive you will obviously bump to one of these sun clocks. Please make sure to document them, as I document them for reference, as they might not be around the next time you come by.