Variously known throughout history as Qir Heres, Qir Moab, and Hareseth, Karak has been a prized possession of a number of civilizations. It lies on the ancient caravan routes that used to connect Egypt to Syria, and its commanding position almost 1000 meters above the Dead Sea Valley made it a strategic asset of great importance. The city was the ancient capital of Moab, and was also used by the Greeks and Romans. During Roman times it was known as Characmoba. But it was not until the arrival of the Crusaders in the 12th century that Karak reached its full splendor. It is recorded that the Crusader King Baldwin I of Jerusalem had the castle built in 1132 CE. With its location midway between Shobak and Jerusalem, Karak formed part of a great line of Crusader castles stretching from Aqaba to Turkey. Karak became the capital of the Crusader district of Oultrejourdain, and, with the taxes levied on passing caravans and food grown in the district, it helped Jerusalem prosper.Even with its impressive defensive fortifications, Karak could not hold out against the forces of Salah Eddin. After the governor of Karak, the infamous Reynaud De Chatillon, broke several truces with Salah Eddin, the Muslim leader responded with a massive bombardment of Karak. De Chatillon, who was captured and executed by Salah Eddin in 1187 CE, was known for throwing his captives off the top of Karak's battlements with wooden boxes over their heads to ensure that they remained conscious until they hit the ground. Salah Eddin's armies besieged and conquered the fortress in 1188, marking the beginning of the Crusaders' loss of power throughout the area.

The Mamluk Sultan Baibars refortified the castle in the late 13th century, and it was also later used by the Ottomans. The fort itself has been partially restored, and is a maze of vaulted passages and rooms. To the west across the moat is the tower from which De Chatillon cast his prisoners to their deaths. The tower in the northwest corner was added by the Mamluks in the 13th century. The multi-storied building at the southern end was the dungeon. To the right of the castle entrance, a stone staircase descends to the museum, which holds one of the many copies of the Mesha Stele, along with Mamluk pottery, and Nabatean and Roman coins. The castle is open free of charge during daylight hours, while the museum is open daily 09:00-17:00 with a 1 JD admission.

The town of Karak lies 129 kilometers south of Amman, or 88 kilometers south of Madaba. Within Karak, numerous small hotels are available. Karak can be reached via the Desert Highway by turning right at Qatrana. However, the King's Highway is the recommended route, as it will take you over one of Jordan's most spectacular sights, Wadi Mujib. About 50 kilometers north of Karak, this canyon is over 1000 meters deep. Wadi Mujib was the "Arnon Gorge" or "Arnon River" of the Bible (Numbers 21: 24; Judges 11: 18), a natural boundary which separated the Moabites in the south from the Amorites in the north.