This small mosque was dedicated to Shaikh Salim Chishti of Sikri. Created by local workmen (quarrymen) from stone quarried along the ridge which would later house Akbar's imperial city, it may have been the first substantial building to be erected on the site.
Sources:
Rizvi, Saiyid Athar Abbas. Fathpur-Sikri. Bombay: D. B. Taraporevala Sons, 1975.
Tillotson, G. H. R. Mughal India, 123. San Francisco: Chronicle Books, 1990.