Athens, 411 BCE
Aristophanes' Lysistrata takes place in the Ancient Greek city of Athens. Actually, that's not quite right: for him, it wasn't the ancient Greek city of Athens; he was writing about his contemporary city. That Aristophanes sure had his finger on the pulse, man. He was the John Oliver of his time.
In fact, the play takes place in the same year that it was first performed: 411 BCE. So what was going on in Athens in 411 BCE? By far the most important event of the day was the long war between Athens and Sparta, otherwise known as the Peloponnesian War. The play appeared at a time when the war was going especially badly for Athens, ever since its massive fleet got massacred in Sicily two years earlier. Ouch.
In such a situation, many people would have felt that the war was a complete disaster, and would have been ready to make peace. In Aristophanes' play, no one feels this more strongly than Lysistrata and the other women of Athens, who decide to take action and force their men to stop the war. Unfortunately, Aristophanes' play wasn't enough to inspire the men and women of Athens to take action (in the way described in the play, or otherwise) and the war dragged on.
Still, the play provides an important window into how people were feeling at this moment in history. It also provides a slightly-more-pervy look into the (bedroom?) window of Ancient Athenian sexuality. And—oh yeah—its comedy still holds up. Erection jokes are hilarious forever, it seems.