Chirag Gala (“Lamp Castle”), a castle from 4th-5th century is located 100 km to the north of Baku on top of a mountain. Chirag Gala was built over a seam of oil and gas which allowed for lighting up signal fires visible to the distance of several dozens of kilometers. Similar castles and towers were located all over the area from Derbent to Baku providing for a warning system against enemy invasions. Today, under the castle, the “Galaalty” urology treatment center is located whose thermal water has a curative effect on diseases of the kidneys, urinary tract and digestive organs.