Don't be fooled by local guides telling you this is the actual place where Socrates drank his poison and spent his last days. They love telling fancy stories, and this is one which is often used.
If it's anywhere, it's in the Athenian Agora. If you want to try to find it, check this website: http://www.fodors.com/community/europe/location-of-socrates-prison-cell-athens-greece.cfm
Then what are you seeing right now? The obvious answer: nobody's sure. The best guess is that this was a Mycenaean building which was subsequently reused for various purposes. The holes in the bedrock were actually used for wooden beams, so the building was most likely in front of what we can see today.
A beautiful place nonetheless, albeit with a very innacurate description. It is a very relaxing place though, with not too many tourists. I still recommend it, even though it's not quite as historically important.
If you own or manage Prison of Socrates, register now for free tools to enhance your listing, attract new reviews, and respond to reviewers.