First constructed in the ninth century, the Mosque of al-Hadi in Sa'da is one of the oldest mosques in Yemen. It is named after Al-Hadi Yahya bin al-Hussain, the founder of the Zaidi dynasty, whose tomb adjoins the mosque. The tombs of eleven of his successors are also found at this mosque.

A typical example of the early mosques in Yemen, this hypostyle mosque is square in plan with a central courtyard. The original ninth-century structure included only the section of the mosque south of the current court. This area has two mihrabs on its qibla wall. It is three bays deep and fifteen bays wide, with a flat roof carried on twenty-eight pillars. It measures approximately eight by forty-five meters.

In the middle of the thirteenth century, a large u-shaped prayer hall was added to the north of the old mosque, creating the mosque that exists today and its rectangular courtyard. This section has a large mihrab that is on axis with the larger of the old mihrabs. An impressive dome, visible from anywhere in the city crowns the mihrab. There is a single minaret inside the court.

To the south of the old sanctuary is a long irregularly shaped courtyard, lined by the domed tombs of the imams of various height and size. Some have mihrabs on their qibla walls. The tomb of Imam al-Hadi was originally open on all sides; it is now surrounded by three other tombs. The profusion of ornamentation and inscription on these tombs is not seen in the prayer hall where decorative treatment is focused on the mihrab.

The new section of the mosque has two entrances with stairs to the east while the old section has a side entrance to the west and doors along the qibla wall that lead into the new section. The courtyard with tombs is entered through entry halls to the east and west.

Sa'da, and the Mosque of al-Hadi in particular, is a well-known center for Islamic theology and, especially, Zaidi teaching. The mosque is the home to priceless manuscripts and books on Islam.

In 2015 it the mosque was reported as destroyed.

Sources:

Finster, Barbara. "An Outline of the History of Islamic Religious Architecture in Yemen." In Muqarnas IX: An Annual on Islamic Art and Architecture, edited by Ann Oleg Grabar, 129, 142. Leiden: E.J. Brill, 1992.

Hämäläinen, Pertti, and Françoise Fauchet. Yémen: guide de voyage, 119. Paris: Lonely planet publications, 1988.

Taylor, Adam. "The World May Be Ignoring the Destruction of Cultural Treasures in Yemen." Washington Post. June 5, 2015. Accessed December 18, 2015. https://www.washingtonpost.com/news/worldviews/wp/2015/06/05/the-world-may-be-ignoring-the-destruction-of-cultural-treasures-in-yemen/.

Yemen Times Online. "Al-Hadi Mosque: Unique Islamic Architecture." Accessed May 26, 2004; inaccessible October 11, 2013. http://www.yementimes.com/01/iss01/lastpage.htm