Capital of the Khorasan province

The holy city of Mashhad is the administrative capital of the Khorasan province. Its present population is nearing two and half millions and occupies an area of more than 200 square kilometers. It is situated in the north-east of Iran between Binalood and Hazar mountain ranges. It is 945 kilometers away from Tehran and its altitude is 980 meters above the sea level. At present Mashhad is the second largest city in Islamic Republic of Iran after Tehran.
In the beginning of the third century Hijrah, Mashhad was a small village called Sanabad, situated 24 kilometers away from Toos. The summer palace of Humaid bin Qahtabah, the governor of Khorasan, during the end of the second century Hijrah was situated in that village. Harun al-Rashid, the Abbasid caliph, in order to put down the insurrection of Rafeh ibn Laith, went on an expedition to Transoxania. In 193 A.H./ 808 A.D., when he reached Toos, he became critically ill and died. He was buried under the hall of the palace of Humaid bin Qahtabah, in the Sanabad village.
The city of Mashhad came into existence when Imam Reza (A.S.), the eighth Shi'ite Emam, after his martyrdom at the hands of Mamun, the Abbasid caliph (born. 786 A.D., ruled. 813-833 A.D.); on the last day of the month of Safar 203 A.H. / 5 September 818 A.D., was buried in the palace of Humaid bin Qahtabah beside the grave of Harun al-Rashid. 
After this event, the mausoleum of Imam Reza (A.S.) became the pilgrimage center of the Shi'ites and the lovers of the Holy Ahl al-Bayt (A.S.) in the world and the small village of Sanabad was soon transformed into a flourishing city called as Mashhad ar-Reza (tomb sanctuary of Imam Reza (A.S.) also briefly called Mashhad. Mashhad literally means a place where a martyr has been buried. 
By the end of the third century Hijrah, a dome was built on the grave of Imam Reza (A.S.) and many buildings and bazaars sprang around the holy shrine. Followers of the Ahl al-Bayt (A.S.), from various parts of the world started visiting Mashhad for pilgrimage. In 383 A.H. / 993 A.D., Sebuktigin, the Ghaznevid sultan devastated Mashhad and stopped the pilgrims from visiting the holy shrine of Imam Reza (A.S.). But in 400 A.H./ 1009 A.D., Mahmud of Ghazni (born 971, ruled, 998-1030 A.D.,) started the expansion and renovation of the holy shrine and built many fortifications around the city.
The holy shrine was decorated with fine marbles, quality wooden and stucco works. Mahmud of Ghazni also built the burial chamber on the grave of Imam Reza (A.S.).This square-shaped building which constitutes the center of the Shrine, before adding decorations and additional parts,had been apparently similar to Sang Bast (Tomb of Arsalan Jadhib), because of their simultaneity. According to the earliest tomb inscription of Imam Reza(A.S.), kept in Astan Quds Razavi Museum, then the Shrine construction might have been reconstructed or repaired in 516/1122. This building was damaged severely during the Ghuzz invasion in 548/1153. 
After him his son Masud (b. 998 A.D., r. 1030-1040 A.D.) built a wall around the holy shrine and further beautified the holy shrine. 
Sultan Sanjar (b. 1086 A.D., r. 1097-1157 A.D.), after the miraculous healing of his son in the holy shrine of Imam Reza (A.S.), renovated the sanctuary and added new buildings within its precincts.
At the time of Sultan Sanjar Saljuqi, after Sharaf al-Din Abu Tahir b. Sa'd b. Ali Qummi repaired the Shrine, he began to construct a dome over it. Later, in 557/1162, however, Chatrgan Zumurrud Malik, daughter of Mahmud Saljuqi, decorated the dadoes with precious hexangular, octagonal and star-shaped tiles. Her name and the date of decoration were inscribed on the tiles.
In 612 A.H./ 1215 A.D., as borne out by inscriptions on certain tiles, Allaudin Khwarezm Shah carried out renovations on the shrine. Two of the prayer niches, embellished with elegant porcelain tiles, as well as those with Kufic inscriptions that adorn the walls to the upper side of the holy burial chamber, bear the name of his vazir Ali bin Muhammad Muqri. A couplet in Persian by Abdullah bin Muhammad bin Abdullah on the wall also carries the date 612 A.H.
During Khwarazm-Shahs peried, Razavi Shrine was paid much attention and some repairment and decoration were made in it. In this era(612/1215), two very glorious embossed thulth (a large Naskh handwriting ) inscriptions in form of square tile work were fixed on both sides of the shrine entrance-by the side of Dar al-Huffaz porch– in which the names and descent of Imam Reza(A.S.) back to Imam Ali (A.S.) were written. Some other inscriptions and three mihrabs(a special place for prayer-leader in mosques) belonging to this age exist in this holy complex. 
During the Mongol invasion in 617 A.H. / 1220 A.D., Khorasan was plundered by the invading hordes and the survivors of this massacre took refuge in Mashhad and settled around the holy shrine. Sultan Muhammad Khudabandeh Iljaitu(b. 1282 A.D), the Mongol ruler of Iran converted to Shi'ism and ruled Iran from 703-716 A.H/ 1304-1316 A.D., once again renovated the holy shrine on a grand scale.
Ibn Batutah who visited Mashhad in 734/1333 mentioned the nice tile decorated building of the Shrine and silver Zareeh(burial chamber) over the tomb which might has been built in Iljaitu period. It also seems that the complete construction of the present dome is one of Iljaitu's services.
In 791 A.H., Miran Shah the son of Tamerlane( b. 1336 A.D., r. 1370-1404 A.D.) razed Toos to its foundation and massacred its inhabitants. Toos lost its popularity. and as a result the holy city of Mashhad rose to prominence contributing to the gradual emergence of Mashhad as a major city.
The glorious phase of Mashhad started during the reign of Shahrukh Mirza (b. 1377 A.D., r, 1405-1447) son of Tamerlane and reached its zenith during the reign of Safavid kings who ruled Iran from 1501-1786 A.D. Shahrukh Mirza, whose capital was Herat, regularly visited Mashhad for the pilgrimage of the holy shrine of Imam Reza (A.S.). His wife Gowharshad Agha in 821 A.H./ 1418 A.D., ordered the building of the famous and historical Gowharshad Mosque, which is one of the biggest and most beautiful mosques in the world. This historical mosque is situated beside the holy shrine of Imam Reza (A.S.). During this period the holy shrine developed into an extensive complex comprising various grand historical monuments.
]
In 8th/14th century, buildings of Astan Quds Razavi included: the Shrine, Bala Sar Mosque (constructed by Abu-al Hassan Iraqi, one of the clerks in Ghaznavi period), some small buildings attached to the north side of the Shrine, and a seminary. 
Then, Dar al- Huffaz, between the shrine and the Mosque, Dar al-Siyadah on the west side of Dar al- Huffaz?, and finally "Tawhid Khanah" or "Khazanah" (public treasury) were built on the east side. In addition, three seminaries: Madrisah Parizad, Madrisah Bala Sar, and Madrisah Du Dar were built round the above-mentioned complex during Shahrukh's rule.
In Sultan Hussein Bayqara's era (875/1470-912/1506), Sahn Atiq (the old courtyard) and the main building of the golden porch were founded by Amir 'Ali Shir Nava'ii. 
With the emergence of the Safavid dynasty in 1501 A.D. and their declaration of the Shi'ite school as the state religion, Mashhad reached the peak of its development and soon became one of the greatest sites of pilgrimage. However, since Khorasan was a border province of the Safavid Empire, Mashhad consequently suffered repeated invasions and periods of occupation by the Uzbek Khans - Muhammad Khan, Abdullah Khan Shaibani, Muhammad Sultan and especially Abdul - Momen Khan. These invasions continued up to 996 A.H./ 1586 A.D., the time of Shah Abbas I, who finally drove out the Uzbeks from Khorasan.
Sahn Atiq was extended in the time of Shah Abbas I , and still, during the Safavids era, great efforts were made for its improvement. Shah Tahmasb Safavi began to repair and gild the minaret near the dome and in 932/1525, precious tiles covering the dome were changed into gold-coated bricks. After they were plundered during 'Abd al-Mu'min Khan Uzbeg invasion, the gold-coated bricks were rebuilt by Shah 'Abbas in 1010/1601, the details of which was written on an enamelled inscription by 'Ali Reza Abbasi. Shah 'Abbas also began to establish northern porch, rooms, chambers, facades, as well eastern and western porches.
It is said that Mullah Muhsin Fayd Kashani ordered to establish Tawhid Khanah portico in the north side of the Shrine. Allahverdikhan portico, porch in the north side of Dar al-Ziyafah(reception chamber) and Hatam Khani portico, all were built in the time of great princes of Safavids, Allahverdikhan and Hatam Beq Ordoobadi. 
Shah Abbas II commanded to repair and tile Sahn Atiq and Shah Sulaiman also ordered the repair of the Holy Shrine Dome which had been splitted because of the earthquake; this can be read in an erected inscription. He also commanded to establish severeal Madrasahs (Islamic Seminaries). The northern porch of Gowharshad Mosque, the Holy Shrine entrance, along with Musallah(place of prayer) located in Payeen Khiyaban (lower street) were repaird and tiled by a skillful Isafahani mason called Ustad Shuja`.
Nadir Shah Afshar (b. 1688, r. 1736-1747 A.D.) and the Qajar kings who ruled Iran from 1779-1923 illuminated, beautified and expanded the various courtyards (Sahn), porches (Riwaq) and places in the holy shrine.
The golden porch of Sahn Atiq and the minaret on its top were repaired and gilded, the minaret of north porch was erected and illuminated; and Sangab (a vessel or container made of single block of marble) in Ismail Tala'ee Saqqa Khanah (a public place for drinking water) was built in Sahn Atiq. All these happened during Nadir Shah Afshar's monarchy.
There have slao been some improvements in Holy Shrine complex during Qajar period, including new courtyard establishment and gilding its porch, both of them started in the time of Fath Ali Shah Qajar and ended in Nasir al-Din Shah's era. The porch and northern façade of Sahn Atiq, as written in the inscription of its top, were also repaired during Muhammad Shah's rule. 
Tawhid Khanah was repaired in 1276/1859 in the time of 'Adud al-Mulk's custodianship. He had the fine paintings and tiles of the Shrine decorated with mirrors in 1275/1858. Nasir al-Din Shah, too, had the gold-coated bricks put up on the walls, from dado up to the top of western proch of the new courtyard and its stalactite-shaped ceiling. So it was called "Nasiri Porch". There was also some repairment in both courtyards, the old and the new one during Muzaffar al-Din Shah's monarchy.
On 10th Rabi al-Thani 1330 A.H. in the year 1911 A.D., the Tsar Russian artillery shelled the holy shrine and martyred a large number of pilgrims and inhabitants of Mashhad.The whole complex greatly in 1330/1911, but it was repaired again after a while by Hussein Mirza Nayyir al-Dawla, Khurasan's governor. 
There happened some essential changes round the complex in 1347/1928, when Falakah (round open space with the radius of 180 meters from the top of the Dome was established. Then they began to build the Museum, the library and the Hall for ceremonies.
Old Falakah was extended up to a radius of 620 meters before the glorious victory of the Islamic Revolution, and and important part of Holy Buildings' historical structure was demolished without considering its antiquity and elegance. 
On 11th Rabi al-Thani 1354 A.H. /13 July 1935, the armed forces of Reza Khan (b. 1878, r. 1925-1941 A.D.), the founder of Pahlavi dynasty in Iran, invaded the holy shrine and massacred innocent people gathered in the Gowharshad Mosque.The people there were protesting against the anti-Islamic rule of Reza Khan for banning Hijab (modest dress) for women in Iran.
During the peak days of Islamic revolution, on 21 st November 1978 Muhammad Reza Shah's (b. 1919, r. 1941-1978 A.D.) troops committed the sacrilegious act of Killing a large number of innocent people within the holy shrine of Emam Reza (A.S.).