Karak is situated on the King's Way, and was the ancient capital of the Moabites. The most visitors come to see the Crusader castle on the hilltop. The fortress was built in the 12th century and ruled by Payen le Bouteiller, the Lord of Transjordan (Oultrejordain).

Karak had been a fortress since biblical times, the King of Israel and his allies from Judah and Edom besieged here the Moabite king Mesha. What to see today is mainly from Crusader times, as its strategic position enabled to control Bedouin herders as well as trade routes from Damascus to Egypt and Mecca. Karak's most famous cause brutal occupant was Reynald de Chatillon, who came in power in 1176. Breaking all treaties, he began to raid caravans and even threatened Mecca. As response Sultan Salah ad Din, the ruler of Syria and Egypt, attacked the castle and finally captured it in 1189.

Karak became the capital of a district covering much of Jordan, playing a central role in Middle Eastern politics for the next two centuries. It was the capital of the whole Mameluk kingdom when Sultan an-Nasir Ahmad grew weary of power struggles in Cairo. His brother and successor Salih Ismail took the fortress and returned the royal insignia. During these sieges Karak was the first target of modern artillery in the Middle East, Salih Ismail used cannons and gunpowder. During the Ottoman rule, the Mameluk palace inside the castle was used as a prison.

The imposing fort consists of stone-vaulted halls and endless passageways; the best preserved are underground. The castle was enlarged with a new west wing added by the Ayyubids and Mameluks. Access to the town was through subterranean passages with entrances still visible today. In the lower court of the castle you can find the Karak Archaeological Museum, introducing local history and archaeology of the region from the prehistoric period until the Islamic era.