October 29: Cyrus the Great, founder of the Achaemenid Persian Empire, conquered Babylon and completed the largest empire that had existed up to that time, in 539 BC, and allowed the Jews to return to their Promised Land.

Nabonidus, last king of king of Babylonia, in relief showing him praying to the moon, sun and Venus; slab in the British Museum.

On October 29, Cyrus himself entered the city of Babylon and arrested Nabonidus, the last king of the Neo-Babylonian Empire.

Artistic portrait of Cyrus the Great. He founded Persia by uniting the two original Iranian Tribes- the Medes and the Persians. Although he was known to be a great conqueror, who at one point controlled one of the greatest Empires ever seen, he is best remembered for his unprecedented tolerance and magnanimous attitude towards those he defeated.

Before the invasion of Babylon, Cyrus had conquered many kingdoms. Apart from Babylon, Cyrus probably incorporated its subnational entities of his Empire, including Syria, Judea and Arabia Petraea, although no direct evidence of this fact was found.

Lands that Cyrus the Great united under Persian rule.

After taking Babylon, Cyrus the Great appointed himself as "king of Babylon, king of Sumer and Akkad, king of the four corners of the world" in the famous Cyrus Cylinder.

Slavery was abolished by Cyrus the Great after conquering Babylon around ~540 BC.

Cyrus was proclaimed in a cyllinder inscription placed in the foundations of the temple Esagila dedicated to the chief of Babylon and its god Marduk.

"The Cyrus cylinder is a fragmentary clay cylinder with an Akkadian inscription of thirty-five lines discovered in a foundation deposit by A. H. Rassam during his excavations at the site of the Marduk temple in Babylon in 1879... It is inscribed in Akkadian cuneiform. Now housed in the British Museum, it includes a detailed account by Cyrus of his conquest of Babylon in 539BCE and his subsequent humane treatment of his conquered subjects. 

The text of the cylinder denounces Nabonidus as impious and portrays the victorious campaign of Cyrus to please the god Marduk. It describes how Cyrus had improved the lives of the citizens of Babylonia, repatriated displaced peoples and restored temples and shrines of worship. Although some have claimed that the cylinder is a form of human rights charter, historians generally portray the context of a Mesopotamian tradition of long standing.

The Persian Empire under Cyrus the Great. http://aclassicaday.blogspot.com.co/2011/11/fall-of-croesus.html 

The domains of Cyrus the Great make up the largest empire the world had seen. At the end of the regime of Cyrus, the Achaemenid Empire stretched from Asia Minor in the west to northwest areas of India in the east.