I studied Shakespeare's Julius Caeser in school and, to this day, I still enjoy it. I think this mostly has to do with how a large number of quotes and references from it, have made their way into popular culture.
Case in point, you may see references to the Ides of March online today, March 15th. This was the day (according to Julius Caeser) that Caeser was assassinated. He was warned by a soothsayer to “Beware the Ides of March”.
I've listed some more memorable quotations below, I'm sure you've come across them at some point.
“Et tu, Brute?”
“It is the bright day that brings forth the adder
And that craves wary walking.”
“Of all the wonders that I have heard,
It seems to me most strange that men should fear;
Seeing death, a necessary end,
Will come when it will come.”
“Cry havoc and let slip the dogs of war!”
“Friends, Romans, countrymen, lend me your ears;
I come to bury Caesar, not to praise him;
The evil that men do lives after them,
The good is oft interred with their bones,
So let it be with Caesar”
“Cowards die many times before their deaths; the valiant never taste of death but once.”
“As he was valiant, I honor him. But as he was ambitious, I slew him.”
Shakespeare references are always fun, especially when used in a modern context. I particularly like the Macbeth reference in Collateral.