The Amphitheatre in Epidaurus on the Peloponnese in Greece lets sounds from the actors to be heard all over the area, even when the structure can seat up to 14,000 people.

Created around the 4th century BC by Polykleitos the Younger, the renowned Ampitheatre is made of 55 semi-circular rows that go up from the area where the actors perform. What makes this place remarkable is that even without a microphone, the actors' voices could be heard clearly.

It's always been thought that the place has been mathematically made to amplify voices. But Georgia Institute of Technology researcher Nico Declercq says nay to this theory and shows his findings about the acoustics of the intriguing building. He says that it's not the shape of the structure itself, but the material it's made of, which deserves credit for the Amphitheatre's amazing acoustics. Limestone has an ability to filter out low frequencies of voices, minimizing background noise and enhancing sound quality in the theatre.

Nico says that the rows of limestone seats also reflect high-frequency sounds back towards the audience, enhancing the sound effect. Now who would have thought of that before? Maybe next time our present-day architects may take the cue of their ancient Greek counterparts. And then, rock music could be better heard on limestone seats.