A cherished religious and cultural landmark, the Eastern Mosque in Al-Yamamah, at the center of Al-Kharj governorate, is a remarkable witness of the enduring Najdi architectural style. According to historical sources, the mosque was constructed between 1050 and 1100 AH. A historical document, now kept by the heirs of the endower Al-Sa'al, who built the mosque on his agricultural land, provides evidence of the mosque's endowment in 1209 AH. The mosque's architectural style was crafted to suit the prevailing climatic conditions of the region. A basement was constructed to ensure warmth for worshippers and students during winter and a cool place from the harsh summer heat. The mosque's roof, built using tamarisk wood, is flat and features a solid, level layer to create a surface that aligns with the niche on the ground floor. This design feature allows secret prayers to be performed in the winter and audible prayers in the summer due to the moderating effect of the climate in the surrounding agricultural areas. Abdulaziz bin Ibrahim Al-Saees, an expert on local history, said that adjacent to the mosque, a room for ablution and washing was constructed and a well was dug in the northwestern section of the mosque to provide water for both the mosque and the local community. The mosque's basement features openings that allow natural light and air to filter in during the day and hangers for lamps to provide illumination at night. The courtyard separates the basement area and the upper mosque, accommodating 40-60 worshippers. The old mosque was last used in 1432 AH due to its need for restoration. As a valuable historical landmark, the mosque required being revamped by experts as part of the government's restoration projects. The locals kept the mosque in its original state, placing barriers around it to protect it against collapsing. However, the mosque's parts have already fallen due to climatic conditions. Dr. Abdullah bin Saad Al-Saal Al-Khalidi stated that the historical document indicates that in the early 12th century, Muhammad bin Sa'al purchased a property in Al-Yamamah using two currencies known as "zerr" and "ahmar." The document reported that a water carrier known as "Al-Hambousiyeh" was endowed to provide water for the village. At the same time, a separate well was allocated for the mosque and its facilities. According to historical documents, the mosque suffered severe damage in 1170 AH, but was subsequently restored. The mosque was constructed using materials sourced from the local environment, including solid, petrified mud veins and a layer of mud mixed with gypsum, a local material boiled to resemble natural gypsum, palm fronds, and twigs. The mosque was last restored approximately 70 years ago.
