This year represents the 30th year of excavations at Metropolis and Dr. Serdar Aybek , head of the department of archaeology at Turkey’s Manisa Celal Bayar University, told Hurriyet Daily News that a team of researchers had unearthed four monumental interconnected subterranean structures . The four water cisterns were found under the acropolis, the highest part of the city, beneath a seven-meter (23-foot) earth fill dating to the Late Roman period, roughly 1,500 years ago. An article in Archaeology News Network says the people of Metropolis built these cisterns during the Byzantine period as an additional water source to the water resources found in the lower parts of the city.