Which country is Akropolis?

Excuse me, could you please clarify something for me? I've come across the term "Akropolis" and I'm a bit confused. Is Akropolis a specific country, or is it perhaps a reference to something else entirely? If it is indeed a country, could you tell me a little bit about it? Perhaps its location, some notable features, or maybe even its history? I'd really appreciate it if you could help me out with this. Thank you!