Ecbatana (/ɛkˈbætənə/) was an ancient city, the capital of the Median kingdom, and the first capital in Iranian history. It later became the summer capital of the Achaemenid and Parthian empires. It was also an important city during the Seleucid and Sasanian empires. Ecbatana was located in the Zagros Mountains, the east of central Mesopotamia, on Hagmatana Hill (Tappe-ye Hagmatāna). Its strategic location and resources probably made it a popular site even before the 1st millennium BC. It is identified with the current city of Hamadan.

According to Herodotus, Ecbatana was chosen as the Medes' capital in 678 BC by Deioces, the first ruler of the Medes. Herodotus said that it had seven walls. Deioces's intention was to build a palace worthy of the dignity of a king. After choosing Ecbatana as his capital, Deioces decided to build a huge and strong palace in the form of seven nested castles. Herodotus says that each of them was in the color of a planet. The royal palace and the treasury were located inside the seventh castle. The outer perimeter of the castle wall was almost the size of the city wall of Athens.

The royal palace, which was built in the last inner fort, had hundreds of rooms and people also built their houses outside of these forts, next to the palace. Some archaeologists have also attributed its construction to Phraortes, the second king of the Medes. Other old legends attribute the origin of Ecbatana to the legendary Semiramis or Jamshid. Ecbatana has also been mentioned by other Greek historians such as Polybius, Ctesias, Justin, and Xenophon. The Assyrians do not seem to mention Ecbatana, and it is likely they never penetrated east of the Alvand despite two centuries of involvement in Median areas of the central Zagros.

In 550 BC, Cyrus the Great defeated Astyages and conquered Ecbatana, forming the Achaemenid Empire. Although Ecbatana lost its former importance, it was located on the royal road, where it connected Persepolis to Sardis, and situated at the foot of Mount Alvand. So it was settled by the Achaemenid rulers. The city became the summer capital and a treasury of the Achaemenids. As mentioned in several sources, the city was also used as a royal archive.

In ancient times, Ecbatana was renowned for its wealth and splendid architecture. In 330 BC when Darius III faced Alexander, Ecbatana was in ruins, but Darius III ordered the construction of hundreds of hiding places in the middle of the city for treasures and assets. Some weeks before Darius III was killed in a coup in July 330 BC, Ecbatana was conquered, and Persepolis destroyed by Alexander. These events marked the end of the Achaemenid Empire.

In 330 BC, Alexander the Great captured the treasury of Ecbatana, and he looted all the gold and silver decorations of the palace. Ecbatana was the site of the assassination of the Macedonian general Parmenion by Alexander's order.

Later, in 305 BC, the city was ruled by Seleucus I. The Battle of Ecbatana was fought in 129 BC between the Seleucids led by Antiochus VII Sidetes and the Parthians led by Phraates II, and marked the final attempt on the part of the Seleucids to regain their power in eastern Iran against the Parthians. After their defeat, the territory of the Seleucids was limited to the area of modern-day Syria.

Ecbatana later became the summer capital of the Parthians, and their main mint, producing drachms, tetradrachms, and assorted bronze denominations.