Scaenae Frons from the Theatre of Dionysus

Origin
The Theatre of Dionysus Eleuthereus is a major theatre in Athens, considered to be the world's first theatre, built at the foot of the Athenian Acropolis. Dedicated to Dionysus, the god of plays and wine (among other things), the theatre could seat as many as 17,000 people with excellent acoustics making it an ideal location for ancient Athens' biggest theatrical celebration, the Dionysia. It was the first theatre ever built, cut into the southern cliff face of the Acropolis, and supposedly the birthplace of Greek tragedy.

The pillars that made up part of the Scaenae Frons, or the backdrop of the stage, were first identified as an artifact during a performance of an unknown play. One of the actors dropped a vase which shattered next to a pillar, the resulting amplified crash deafening all on stage and most of the first few rows. Though all twelve pillars were moved during renovations in 299 BCE, only one full and two fragmented remain.

Effects
The pillars of the Scaenae Frons amplify sound impressively, eroded and aged as they are. Regardless of the area the pillars provide perfect acoustics. They seem to be activated by melodic tones or the commencement of a recital and after being activated will remain so for several hours.

As discovered during the incident that had them collected, sudden loud sounds when in an active state are also magnified, potentially causing serious damage to nearby persons.