Gowharshad Mosque is a mosque in Mashhad located in southern part of the Holy Shrine of Imam Reza Complex. The mosque was built in Timurid period by the order of Gowharshad-Agha, the consort of Timurid monarch Shahrokh.¹ Its construction was completed in 821 AH, when Shahrokh formally inaugurated it.² This date is repeated in three inscriptions located in different parts of the southern ivan.³ According to the mosque's endowment document (waqf-nāma), its construction is dated 829 AH and the names of Shahrokh and Gowharshad-Agha are mentioned as the commissioners of the mosque.⁴ In another inscription in southern ivan, Qavam ed-Din Shirazi is named as the architect of the building.⁵ Shahrokh's son⁶, Baysonqor Mirza, and Mohammad-Reza Emami⁷ are among the calligraphers of the mosque's inscriptions. Before the construction of present mosque, there was another mosque in place of it which an old woman had built out of her permissible properties and was therefore known as Masjed-e Pirzan (Old Woman's Mosque).⁸ According to Merʿat ol-Boldan, the perimeter of the mosque in Qajar period was also famous as Masjed-e Pirzan.⁹ The present building was built during the expansion of shrine in Timurid period. It has been repeatedly restored in different periods and its inscriptions indicate restorations made in Safavid, Afsharid, Qajar, and Pahlavi periods. The mosque is a four-ivans building that the dimensions of its square-shaped courtyard is 52x56 meters and it has a two-storey peripheral facade. The ivan facing qibla is rather deep and there are two minarets on its both sides and a domed hall behind it. There is a big prayer niche in the domed hall covered with mosaic tiles and there is a muqarnas-adorned ceiling above it. The northeastern not deep ivan is known as eyvan-e-sadeh and is connected to Dar ol-Siada portico; however its northwest and southeast ivans are quite deep. The facades of the courtyard are covered with various forms of mosaic tiles and their background colors consist of cobalt blue and turquoise. In the past, there was a platform amid the courtyard surrounded by four pools and the water of a qanat bequeathed to the mosque in Safavid period entered from one side and existed from the other.¹⁰ Essential repairs were made in the mosque between 1329 and 1346 AS, specially when the shrine of Imam Reza (pbuh) came under cannom fire in 1330 AS, so that the mosque's dome and ivans were rebuilt in concrete and its porticos and hypostyle halls were totally repaired. The entrances of mosque, among the ensemble buildings of the Holy Shrine, have also been exposed to alteration.