Problem statement: Despite being very old and remaining from the early Islamic, Seljuk, Ilkhanid, and Safavid eras, the Jame Mosque of Saveh has not been investigated as it deserves. The results of the research done to date are minimal and contain ambiguities that should be revised. In the recent field visit on 2022/5/25, points were discovered that have not been mentioned in any article or report to date, including things about the Chartaqi, the decorative plaster in the first pillared nave, the naves around the mosque, and the triple plaster altars along the Qiblah altar.Research objective: To develop the original model of the mosque based on the historical background of the building and its evolution in different eras, it is necessary to review the existing opinions and resolve the ambiguities based on the recent field visits.Research method: This study employed the historical-documentary method and data collection was carried out using the library and field method (interview with researchers and field visit). To address some ambiguities and contradictions. Then, the information was classified, and will be matched with the latest findings.Conclusion: Saveh Jame Mosque is one of the old mosques of Iran, with a pillared nave (model of the Prophet's mosque) and works from the Seljuk, Ilkhani, Safavid, and Qajar eras, which, although it has unique features, is still in the aura of Ambiguity remains. The evidence dates the building probably before the Fahraj and Tarikhaneh mosque. Opinions about the existence of the fire temple have also been in the history of the mosque, but no documents have been provided for any of them. The recent findings showed new points in this regard, which will be the answer to some ambiguities and a guide for future research.