Cicero's On the Republic
Details
On the Republic (De re publica) is a dialogue on Roman politics by Cicero, written 54-51 BC. Cicero uses the work to explain Roman constitutional theory. Written in imitation of Plato's Republic, it takes the form of a Socratic dialogue in which Scipio Aemilianus takes the role of a wise old man.
Unlike Plato, Cicero doesn't believe that any of the 'pure' forms of government are stable. Instead, he uses the Roman Republic as an example of more stable State with a constitution based on a combination of monarchy, aristocracy and democracy.
As far as political philosophy goes, this is the document from which the US founding fathers derived the form of the Federal government. Now, there is obviously not a one-to-one correspondence between the Constitution of the late Roman Republic and that of the US. But, when you read Cicero's On the Republic, you will find the similarities striking.
And, yes, this will be another play. Conveniently, Cicero wrote On the Republic as a dialogue. So converting it to a play is really just editing (my favorite kind of script writing).
Togas are not a must, but are encouraged. ;-)