The Theater of Dionysus, on the southern slope of the Acropolis, is ancient Greece's most significant outdoor theater and the world's oldest known theater. It was the hub of Athenian drama education and hosted the Great Dionysia, the city's grand religious celebration. This massive structure, part of the Dionysus Eleuthereus Shrine, dates to the 4th century BC but incorporates elements from the Peisistratid dynasty in the 6th century BC. Multiple alterations over time make it challenging to ascertain its original form. The theater could accommodate around 15,000 spectators seated in rows. Today, only 13 rows from the central line of the Classical era remain, along with remnants from the Roman period. A restoration project, initiated in 2002, is underway, adding 13 new stone seating rows from Corinth.