The Ancient Theater of Epidaurus, built in the 4th century BC, is considered the most perfect ancient Greek theater in terms of acoustics and aesthetics. It could seat up to 14,000 people. Modern acoustic studies have revealed that the secret to its sound lies in the limestone seats. The rows of seats act as a natural acoustic filter, suppressing low-frequency background noise (like the murmur of the crowd) while reflecting and amplifying high-frequency sounds from the stage. This allows a spectator in the back row, nearly 60 meters away, to hear a performer's whisper or the sound of a match being struck in the center of the 'orchestra' (the performance floor) without any electronic amplification.