The Constitution of the Athenians (Athenaion Politeia) names either of two texts from classical antiquity, one probably by Aristotle or a student, the other falsely attributed to Xenophon. The Aristotelian text is unique. It isn't part of the Corpus Aristotelicum. It was lost until two leaves of a papyrus codex carrying part of the text were discovered in Oxyrhynchus, Egypt in 1879 & published in 1880. A 2nd papyrus was purchased in Egypt by a US missionary in 1890 & acquired by the British Museum later that year. The 1st edition by Frederic G. Kenyon was published in 1/1891. Editions of the Greek text in widest use today are Kenyon's Oxford Classical Text of 1920 & Mortimer H. Chambers' Teubner edition (1986, 2nd edition 1994).
Ancient accounts credit Aristotle with 170 Constitutions of various states. It's assumed these were research for the Politics & that many were drafted by students. Athens, however, was a particularly important state where he lived at the time. It's plausible Aristotle did one himself, possible it was intended as a model for the rest. If genuine, it's the only one of his extant writings actually intended for publication.
Because it supplys so much contemporary information previously unknown or unreliable, historians have claimed that "the discovery of this treatise constitutes almost a new epoch in Greek historical study." In particular, 21-22, 26.2-4 & 39-40 contain factual information not found in other extant texts.