Now that his kingdom was secured, he reorganized the subject countries in twenty satrapies (provinces), established new taxes, built new roads and a new capital (Persepolis). In fact, he was the architect of the Persian empire, which would remain more or less the same until it was destroyed by the Macedonian king Alexander the Great in the years between 335 and 328.
In 514, Darius tried to subject the European Scythians, who were living in Scythia. It was a disaster. No less disastrous was his Greek policy, which caused a rebellion in the west of modern Turkey in 500 BC. Since the Asian Greeks had received support from the Greek towns Eretria and Athens, Darius launched a punitive expedition in 490; his army, however, was defeated at Marathon. (The story of the revolt of the Asian Greeks and the battle of Marathon can be found in the sixth book of Herodotus' Histories.) Still planning a new, bigger war against the Greeks, Darius died in 486 and was succeeded by his son Xerxes.
Darius was buried at Naqsh-i-Rustam. The inscriprion on his tomb (see picture) reads:
A great god is Ahuramazda, who created this earth, who created yonder sky, who created man, who created happiness for man, who made Darius king, one king of many, one lord of many.
I am Darius the great king, king of kings, king of countries containing all kinds of men, king in this great earth far and wide, son of Hystaspes, an Achaemenian, a Persian, son of a Persian, an Aryan, having Aryan lineage.
King Darius says: By the favor of Ahuramazda these are the countries which I seized outside of Persia; I ruled over them; they bore tribute to me; they did what was said to them by me; they held my law firmly; Media, Elam, Parthia, Aria, Bactria, Sogdiana, Chorasmia, Drangiana, Arachosia, Sattagydia, Gandara, India, the haoma-drinking Scythians, the Scythians with pointed caps, Babylonia, Assyria, Arabia, Egypt, Armenia, Cappadocia, Lydia, the Greeks, the Scythians across the sea, Thrace, the sun hat-wearing Greeks, the Libyans, the Ethiopians, the men of Maka and the Carians.
King Darius says: Ahuramazda, when he saw this earth in commotion, thereafter bestowed it upon me, made me king; I am king. By the favor of Ahuramazda I put it down in its place; what I said to them, that they did, as was my desire. If now you shall think that "How many are the countries which King Darius held?" look at the sculptures [of those] who bear the throne, then shall you know, then shall it become known to you:
the spear of a Persian man has gone forth far; then shall it become known to you: a Persian man has delivered battle far indeed from Persia.
Darius the King says: This which has been done, all that by the will of Ahuramazda I did. Ahuramazda bore me aid, until I did the work. May Ahuramazda protect me from harm, and my royal house, and this land: this I pray of Ahuramazda, this may Ahuramazda give to me!
O man, that which is the command of Ahuramazda, let this not seem repugnant to you; do not leave the right path; do not rise in rebellion!