One hour of driving away from Istanbul, the largest city of Turkey, this area is the first developed sport climbing area in the country. The rock is loose on rarely climbed routes, otherwise solid. There is a very good guide book (ISBN 975-8293-33-8) of the area written by people who developed the area. Unfortunately, I don't have it with me so I am writing all the information from my memory. I apologize for any missing information such as first ascencionists etc. I didn't miss anything technical about the routes. I didn't enter anything I wasn't sure about. So you can trust what you read. If you need a guide for the area, send me a message, I might be able to arrange something.
From istanbul: Drive on TEM towards Ankara (east) take "Gebze" exit. Continue and pass Gebze. Approximately 10 km. outside Gebze, Make a right towards "tavsanli", keep right on the fork. Go through the village, make a right towards a bridge. After a few curves, you will see the "Ballikayalar Park" sign on your left. Follow the sign until you reach a parking lot. The officer will want you to pay 15 TL (might change). If you say you are a climber, he might accept less money.