Derinkuyu is Connected to Other Networks

Citizens of Derinkuyu weren’t the only people who looked for protection against people who sought to cause them harm. There have been plenty of other tunnels and undergrounds networks that have been discovered since that connect to Derinkuyu. These tunnels led the researchers to neighboring cities but they only had at most 3 levels. In the events of the city being overrun by invaders, there were still plenty of tunnels for the 20,000 residents of Derinkuyu to run to.