Greatest Philosophical Works

What are, in your opinion, the greatest philosophical works that exist, and/or what are, as far as you know, generally perceived to be the greatest philosophical works that exist?

The particular branch of interest would be that of Epistemology, but works that apply to any particular branch or all branches would be greatly appreciated.

Thanks in advance. 😄

I'm essentially planning to become an absolute master of the subject so if there are any other approaches that you would recommened feel free to suggest them.

Edit - Also, are there any particular philosophers you would recommend?

The literal greatest works are probably relatively obscure. Those that would be considered culturally "great" would be due to their popularity or cultural influence (present day or in their time). For an easy example, something like Thus Spoke Zarathustra, which is even internally inconsistent with itself at times, probably isn't among the most coherent or "greatest" works of all time. But few can deny it's influence and longevity, which would rank it among the highest if that's your criteria.

As such, I'm probably unable to answer your question sufficiently. Good luck though.

John Norman's Gor series, probably best to read Plato's Republic beforehand for background.

People don't tend to see them as the same thing any longer, but imho, the only epistemology that is worth reading is in the form of Philosophy of Science, and if you can stomach it, statistics.