Im a big fan of "Julius Ceaser" by Shakespeare. Many of Shakespeare's plays make reference to greek mythology and roman history. My broader question is, how did western europeans come to know so much about roman and greek history, especially specific events like Caeser's assasination?
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featuring /u/texpeare:
How familiar would contemporary audiences be with the basis of Shakespeare's history plays?
How much of Shakespeare's 'Julius Caesar' is historically accurate?
other
they found out about these things in the same way as we would learn about them today: by studying the primary sources from the times an places in question. The assassination of Julius Caesar, being a key event in the end of the Republic/birth of the Roman Empire, was written about extensively by writers of the Imperial era, notably in Plutarch's Lives and Suetonius' Twelve Caesars.
Greek mythology would have been very well known to Shakespeare thru immortal and deeply-studied sources like Homer and Hesiod, plus Greek tragedy, Greek philosophy, Greek history, Greek art (the ancient Greeks left a lot) aswell as later compendiums of myth by Pseudo-Apollodorus.