Al-Okhdood, the historical landmarks of Al-Okhdood in the city of Najran tell the story of human settlements in the region from the first millennium B.C. to the end of the fourth century A.D. The period led to a flourishing civilization in Southern Arabia in the most important stop along the ancient incense trade route. Al-Okhdood’s 5-kilometer archeological area falls in the middle of residential neighborhoods located in Najran. The square castle has two main gates connected by a corridor, on both sides of which are rooms and sub-corridors. Many symbols, writings and rock drawings are engraved throughout the castle. In the northeastern part of the site is a large granite millstone that was used for grinding food grains within the market and mosque area. It was discovered in 1996. Excavations began at Al-Okhdood at the end of the 20th century. Archeologists discovered many artifacts and graves, some of which date back to B.C. Some artifacts found in the site’s southern side date back to early Islamic periods. The main fortress, Al-Hosn, contained inscriptions, animal and human drawings, and names of people engraved on the walls. Excavators also discovered a mosque dating back to the first Hijri century on the northern side of the site, in addition to stone tools that were used by humans since the Stone Age. Pottery, glass, and jewelry made from silver, copper and gold were also discovered.