Odeon of Herodes Atticus

(Located on the southwest slope of the Acropolis)
The Odeon of Herodes Atticus is a stone Roman theatre structure located on the southwest slope of the Acropolis of Athens, Greece. The building was completed in AD 161 and then renovated in 1950.

Ancient times
It was built in AD 161 by the Roman citizen Herodes Atticus in memory of his Roman wife, Aspasia Annia Regilla. It was originally a steep-sloped theatre with a three-story stone front wall and a wooden roof made of expensive cedar of Lebanon timber. It was used as a venue for music concerts with a capacity of 5,000. It lasted intact until it was destroyed and left in ruins by the Heruli in AD 267.

Modern events
The audience stands and the orchestra (stage) were restored using Pentelic marble in the 1950s. Since then it has been the main venue of the Athens Festival, which runs from May through October each year, featuring a variety of acclaimed Greek as well as International performances.
Source : Wikipedia 
https://www.youtube.com/watch?v=mzp3Ka4Yn-4
https://www.youtube.com/watch?v=Gav6zpE7nls
Reviews
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Opening hours : 08 AM to 08.00PM
Entry : A normal entry pass to just sightsee will cost 20 Euros (1598 INR) or a reduced 10 Euros (799 INR). One can also buy the Acropolis special ticket for 30 Euros (2397 INR)