Sardis or Sardes (; Lydian: Sfard; Sardeis; ) was an ancient city at the location of modern Sart (Sartmahmut before 19 October 2005) in Turkey's Manisa Province. Sardis was the capital of the ancient kingdom of Lydia, one of the important cities of the Persian Empire, the seat of a proconsul under the Roman Empire, and the metropolis of the province Lydia in later Roman and Byzantine times. As one of the Seven churches of Asia, it was addressed by John, the author of the Book of Revelation in the Holy Bible, in terms which seem to imply that its population was notoriously soft and fainthearted. Its importance was due first to its military strength, secondly to its situation on an important highway leading from the interior to the Aegean coast, and thirdly to its commanding the wide and fertile plain of the Hermus.