The cache is a small air-tight food container, the best thing money can buy around here. We did our best to hide it in such a way that only newbies should experience the pleasure of an FTF, experts please come by next summer, we'll have something special in the box by then, just for your kind understanding (rolling eyes plz).
We could also write many things for the ancient theater of Sikyon but Google and Wikipedia are waaaaay more educated than myself. Spend some time to seek info and you'll see the numbers and the facts why is among the biggest ones in Greece, not to mention it has been built in a very peaceful place with a beautiful view. Try 3D GoogleEarth and get an idea of what will be there for your eyes to see.
There are some special structures around, either geological or man-made to explore. In one of them is, let's say, hidden the cache. If you see it right away, pretend it's not there and make a couple of circles around the area, then return to the cache's nest and feel free to fest accordingly. Of course I'm jokeing, it's not so easy that I want you to believe.