Even though there is a minority of the American population who can decipher what exactly Shakespeare is trying to say in every line of Julius Caesar (e.g. English teachers and the like), the resounding majority is lost halfway through the first scene (e.g. English students). Therefore, when looking for the modern significance of the play, one cannot look at any particular lines, but must look at the so-called "big picture" of the play. And what this is (aside from being probably the only thing that the majority can understand about Julius Caesar) is basically the mood of Ancient Rome and the mood of the Renaissance. And of course, this is because the setting of the play is Rome and the time that William Shakespeare wrote the play was during the Renaissance.
To begin, because it is probably the more important of the two, we will examine what the play tells us about Ancient Rome. At the time that the play takes place, Rome had recently (and when I say recently I actually mean a matter of a few years) been removed from a Republic and had been transformed into a Triumvirate. And on top of that and even more recently, the Triumvirate had been reduced into just one member of the Executive Branch, with that sole member being Julius Caesar. This is where the play gives us some insight. Julius Caesar had taken control by defeating Pompey in a military campaign and the fact that the Roman people were so behind Caesar even though he took down another popular leader shows how much military conquest was respected in these times; the strongest was considered the best and because Caesar was the better military leader he was thought to be the better governmental leader as well. The resent felt by Cassius and his group of conspirators also shows the enlightenment of the Roman people in that although the majority thought one way, free thinking was encouraged and it often led to new ideas (which in this case eventually was the development of an empire).
The play also tells us much about the Renaissance. It was a period of rebirth of Roman and Greek culture which meant that people of the Renaissance obviously respected the Romans. This is seen in the way that Shakespeare glorified the Roman leaders in the play through the proud way he made them stand and speak. The play also reveals the way that Renaissance man wanted to be like Roman man. This was done in the way that Shakespeare put things from his time such as watches into the Roman culture. This shows that the respect Renaissance man had for Ancient man was to the point where they would have liked to think that the two cultures mirrored each other (hence the anachronisms).
Thus, the significance of the play in today’s world is that it shows Modern man the aspects of two past cultures. It shows the proud and enlightened culture of Ancient Rome and it shows the respectful, envious culture of the Renaissance.