Istanbul Professional League 1
Istanbul Professional League was a Turkish football league that operated in Istanbul, Turkey.
The league formed after professional football in the country began in 1952. There were initially 10 teams. It was also known as Istanbul Professional League 1, after Istanbul Professional League 2 was formed in the 1956-57 season. The team who finished the Istanbul Professional League 2 in second place was promoted to PL1, while the PL1 team who finished in last place moved to PL2. Istanbul Professional League was later replaced by Istanbul Local League.