One of the interesting things people notice about Chios are the many Medieval watchtowers scattered along the coastline. The west and southwest coasts have some of the best preserved examples of these towers, called vigles (βίγλες). They were used between the 11th and 19th centuries for the defense of the island.
A vigla had no entrance. The watchmen had to climb up using a rope. Each one was about 12-20m tall and filled with rubble 2/3 its height. From each tower, watchmen could see the next tower on each side up and down the coast. If a pirate or enemy approached, the watchman would light fires or send smoke signals to notify the other towers, allowing the villagers to quickly prepare for an attack.