 The Fortress of Alamut, which was officially called "kursī ad-Daylam" (, literally "Capital of Daylam") on Nizari coins, was thought impregnable to any military attack, and was fabled for its heavenly gardens, impressive libraries, and laboratories where philosophers, scientists, and theologians could debate all matters in intellectual freedom.The hierarchy ("hudūd") of the organization of the Nizari Ismailis was as follows