The Cyrus Cylinder is one of the most famous objects relating to ancient Persia and has become an icon in modern-day Iran. It was discovered in Babylon in March 1879, having been placed in the foundations of the city wall soon after Cyrus's conquest of the city in 539 BC.

The text on the Cylinder is written in the Babylonian language, presumably on the orders of Cyrus himself. It tells us that the previous king of Babylon, Nabonidus, had rejected the Babylonian gods, especially Marduk, the patron god of the city. Marduk had chosen Cyrus to rescue Babylon and to restore the city's gods. Cyrus claims that he has restored temples and cults in neighbouring countries and has returned their deported people and gods. Therefore this object is often linked to Cyrus' permission for the exiled Jews at Babylon to return to Jerusalem, as related in the Bible in the Book of Ezra.

With its references to just and peaceful rule, and to the restoration of deported peoples and their gods, the Cyrus Cylinder has been seen as an early 'charter of human rights'. However, modern scholars have noted that such a concept was quite alien to Cyrus and his contemporaries. Yet certainly the return of the Jews and other deported people showed that he was more tolerant than earlier Babylonian and Assyrian kings.

The Cylinder has become part of Iran's cultural identity, despite being a Babylonian document in origin. It has appeared on postage stamps and bank notes and was displayed in Tehran and at Persepolis during the 1971 anniversary celebrations. Many replicas have been made.