The caliphs of the Arab dynasty established the first schools inside the empire which taught Arabic language and Islamic studies. They furthermore began the ambitious project of building mosques across the empire, many of which remain today as the most magnificent Mosques in the Islamic world, such as the Umayyad Mosque in Damascus. At the end of the Umayyad period, less than 10% of the people in Iran, Iraq, Syria, Egypt, Tunisia and Spain were Muslim. Only on the Arabian Peninsula was the proportion of Muslims among the population higher than this.