روز بزرگداشت خواجه نصیرالدین طوسی / روز مهندستقویم علمی ایران

Khajeh Nasir al-Din Tusi is a seventh century Iranian poet, philosopher, theologian, jurist, scientist, mathematician and astronomer. In honor of the birthday of this great scientist, the 5th of Esfand has been named as Engineer's Day.