of Karbala, whose heads were brought to the Mosque after their defeat at the hands of the then Umayyad caliph, Yazid I. In 2001, Pope John Paul II visited the mosque, primarily to visit the relics of John the Baptist. It was the first time a pope paid a visit to a mosque. On March 15, 2011, the first significant protests related to the Syrian civil war began at the Umayyad Mosque when 40–50 worshipers gathered outside the complex and chanted pro-democracy slogans. Syrian security forces swiftly quelled the protests and have since cordoned off the area during Friday prayers to prevent large-scale demonstrations. Architecture The ground plan of the Umayyad Mosque is rectangular in shape and measures by . A large courtyard occupies the northern part of the mosque complex, while the prayer hall or haram ('sanctuary') covers the southern part. The mosque is enclosed by four exterior walls which were part of the temenos of the original Roman temple. Sanctuary Three arcades make up the interior space of the sanctuary. They are parallel to the direction of prayer which is towards Mecca. The arcades are supported by two rows of stone Corinthian columns. Each of the arcades contain two levels. The first level consists of large semi-circular arches, while the second level is made up of double arches. This pattern is the same repeated by the arcades of the courtyard. The three interior arcades intersect in the center of the sanctuary with a larger, higher arcade that is perpendicular to the qibla wall and faces the mihrab and the minbar. The central transept divides the arcades into two halves each with eleven arches. The entire sanctuary measures by and takes up the southern half of the mosque complex. Four mihrabs line the sanctuary's rear wall, the main one being the Great Mihrab which is located roughly at the center of the wall. The Mihrab of the Sahaba, named after the sahaba ('companions of Muhammad') is situated in the eastern half. According to the 9th-century Muslim engineer Musa ibn Shakir, the latter mihrab was built during the mosque's initial construction and it became the third niche-formed mihrab in Islam's history. The central dome of the mosque is known as the 'Dome of the Eagle' (Qubbat an-Nisr) and located atop the center of the prayer hall. The original wooden dome was replaced by one built of stone following the 1893