The Masmak (Arabic: Qaṣr al-Maṣmak قصر المصمك) is a clay and mud-brick fort, with four watch towers and thick walls, founded on stone blocks, lying in the center of Riyadh, in the old quarters. This building played a major part in the kingdom's history, as it was here that the recapture of Riyadh, led by Ibn Saud, occurred on January 14, 1902.
This building was built around 1865 under the reign of Mohammed ibn Abdullah ibn Rasheed (1289–1315 AH), the ruler of Ha'il to the north, who had wrested control of the city from the rival clan of Al Saud. In January 1902 the young Amir Abd al-Aziz ibn Abd al-Rahman ibn Faisal Al Saud, who was at the time living in exile in Kuwait succeeded in capturing the Masmak fortress from its Rashid garrison. The event, which restored Al Saud control over Riyadh, has acquired almost mythical status in the history of Saudi Arabia and has been retold many times, but has as its central theme the heroism and bravery of the future King Abd al-Aziz.
Among the companions of the Amir were Abd al-Aziz ibn Musa'id ibn Jiluwi, Abdallah ibn Jiluwi, Abd al-Aziz ibn Abdallah ibn Turki, the Amir's brother Muhammad ibn Abd al-Rahman, Abdallah ibn Ibrahim ibn Abdallah Al Saud (nicknamed Snaitan), Fahd ibn Ibrahim ibn Abd al-Muhsin Al Mushari and Nasir ibn Farhan ibn Saud Al Farhan.
Today the fort is one among several buildings that form the King Abd al-Aziz Historical Centre, a series of restored buildings in Riyadh. Centennial celebrations were held in 1999.
It's palm tree gate is 3.65 meters (12.0 ft) high by 2.65 meters (8.7 ft) wide. There is an opening on the center of the door, called al-Khokha, which is just big enough for one person to pass at a time, and is a defensive feature designed to allow people in and out without opening the door. The castle also encloses a mosque and a well. The roofs are covered with painted palm-tree, taramic and ethel wood, the communicating doors of the labyrinthine rooms and courtyards inside are of painted wood.
The building received some important renovation in the 1980s, and became a museum in 1995. The museum includes a display on many antique guns, costumes and agriculture artifacts.