That day, the German band Scorpions will give a live gig together with the Athens State Orchestra.
The concert will take place at Panathenaic Stadium, where, in 1896, the re-birth of the Olympic Games took place.
I have seen Scorpions 3-4 times in the past, but because my wife never saw them and because the stadium is almost next to my home, I decided to go.
The tickets prices vary from 18€ up to 80€. But as far as I know, the "cheap" tickets (18€, 25€ & 28€) are sold out, so the cheaper available now cost 35€ and 40€.
You can find tickets here: https://www.ticketservices.gr/event/scorpions-once-in-a-lifetime/?lang=en
So, if you live in Athens or you are just visitors, try not to miss this event. Scorpions' concerts are always enjoyable and on stage they give 100% of their energy. Not to mention that you will see it in a historical and very beautiful place. (You can see Panathenaic Stadium in the pic below).