What do Greeks do after 3pm?

Everything seems to close at 2 or 3pm here.

Banks all close at 2pm.... that's okay.

I walked to see the National Archeological Museum yesterday, and they had already closed at 3pm (apparently, despite 80 degree and humid weather, they're still on "winter hours").

I wanted to try the museum again tomorrow (skipping some morning talks), and to check out the Acropolis afterward (requires a literal hike). And, guess what? The Acropolis closes at 3pm.

Why in the world would an archeological monument, which apparently doesn't even have a visitors' center somehow, close at 3pm? Does that mean you're not allowed to hike there anymore?

Hmmm.... the Greeks must be having a big party after 3pm every day that I haven't found yet...