Legend has it that Tsarevich Siyavush married a daughter of the Afrosiab Tsar and raised the fortress known as the Ark, initiating the city of Bukhara, an ancient city boasting a history of more than two thousand years.
Data of the archeological digs is quite common, given that the period of medieval Bukhara has been adequately studied; however, information on the early history of this city is rather scant. Archeological investigations show that a large settlement had already existed on the territory of present Bukhara. It is very difficult to unearth valuable clues because Bukhara, in contrast to many other Central Asian cities, has always remained on the same place, so new constructions have been built over ancient monuments.
As a feudal city, Bukhara began to establish itself as a city as far back as the 6th century when the Turkic leader Shiri-Kishvar, after stifling a rebellion of the poor, made the city his capital. At that time a city named Numidjgat arose in the lower regions of Zeravshan, at a place where the river had already given its water to the fields and gardens. The indigenous population of Bukhara was then of Iraqi origin, the people practiced Zoastrism which meant the existence of a fire sanctuary.
In the 7th century the ruler Bidun restored the Ark and built a castle that “according to the plan, was similar to the Great Bear constellation”. Since that time this fortress become the centre of feudal Bukhara: the palace, the government offices, a temple, the treasury and a prison were al located in the Ark. A city began to grow around the citadel  Shakhristan , surrounded by the fortress walls. Registan Square stretched from the west, behind which were the manors with their green gardens, then the fortified castles rising about the skyline of the city. Outside Shakhristan the commercial and craft centre (rabad) began to form. This was incorporated within the city walls in 850.
These walls did not protect the city from the army of the Arab caliphate ruler's invasion. An entire century in the history of Bukhara concerns Arab conquests which had a marked effect on the city's life. Considering constant military operations over such a long period of time as well as numerous rebellions, no serious damage was caused: the city was never taken by storm or plundered. Bukharans were always able to hold the strongest defense and ensure peace for its citizens.
After the Arabs came Genghis Khan. The Mongol invasion turned this flourishing oasis into a mass of ruins. As noble Bukhara was given up to plunder, the largest part of the city was burnt to the ground; only the mosque and some brick palaces survived the fire. However, neither wars nor discords of the local feudal lords could stop the development of Bukhara which continued to grow at an incredible rate. Building didn't stop even after Bukhara, being part of the Tamerlane Empire, lost its political significance and faded into the background because of Samarkand being the new capital.  After the Tamerlane Empire collapsed and the country was conquered by Uzbeks, Bukhara gradually began to gain significance as a metropolitan area once again.
The earliest surviving monument in Bukhara is the Samanid Mausoleum. Folk legend connects the mausoleum's construction with the name Ismail Samani, the most outstanding ruler of this dynasty, ruling between 892 and 907 however, scientists have concluded that many representatives of this dynasty were buried here. The architectural composition of the building is very simple: a cube topped with a hemisphere. The thickness of the walls is a little less than two meters and it is because of this that the mausoleum has stood fast. All the facades of the burial-vault are the same: in the middle of each wall there is a big lancet arch included into the ornamental rectangular curve made of brick circles. Along the top of the mausoleum, on each side is an arch extending from the big lancet windows. The intricate filigree brickwork transforms this simple architectural form into an artistic masterpiece, creating an impression of lightness and elegance.
For almost nine centuries the Kalyan Minaret (Great Minaret) has been towered over ancient Bukhara, seen from afar, irrespective of which side of the city one approaches. It was built by Karakhanid Arslan Khan after the old minaret, situated at the citadel's walls, was destroyed and the mosque relocated to the side of the city. The Kalyan Minaret's unique design was subject to numerous imitations after its construction - despite its monumentality, it possesses perfect proportions. The minaret represents a massive, slightly diminishing column made of square burnt brick made of an alabaster solution. It is crowned with a stalactitic cornice, on which a circular watchtower was built with sixteen lancet windows overlooking every possible direction. The Minaret is connected to the Kalyan Mosque with a bridge from which you can get inside the tower. By climbing the narrow, steep staircase, consisting of one hundred and five steps that go up to the rotunda one can enjoy a magnificent view of the entire city of Bukhara. Five times a day, through sixteen open arches, the muezzins' voices called true followers of Islam to prayers. This was not the only purpose of the “Great Minaret”: other purposes included being a watchtower for possible enemies approaching the city and later, during the 17-19th centuries, this forty-six-meter-high tower became the “Tower of Death”  prisoners were thrown to their death from the top of the Minaret as a form of public execution.

The Kalyan Mosque itself has survived several stages of reconstruction, but the building dates back to 1514, when the first Sheybanids ruled in Central Asia. It is also called the “Djuma Mosque” (Friday Mosque), and is one of the most grandiose mosques throughout Central Asia. Size-wise it is almost the same as the Central Mosque in Herat, which was rebuilt in the 15th at the order of the great Uzbek poet and patron, Alisher Navoi. The mosque Kalyan occupies a large area: 180 by 130 square meters surrounded by galleries and a traditional garden. The cupola galleries boast 288 cupolas are based on the mighty columns of the Mosque, and inside the gallery semi-darkness and coolness reign. This Mosque can house up to 10 000 men and has done so during special celebrations..
Emir Palace on Registan Square is a small, but high and inaccessible fortress with only one gate. During the Middle Ages, its entrance consisted of a steep ramp rising upwards towards the tower gates. In one of the palace walls, at an inaccessible height, is a window through which the Emir made public appearances. Underneath was the Bukhara arsenal: a small canopy from which the cannons looked out. At the entrance gate a huge lash (kamchin) would hang as a symbol of the Emir's power. In the upper circle of the Ark gates, the trophy chimes that were removed from Kokand were installed, chiming every hour. Inside the citadel, under the ramp, were the terrible “kanakhona”  prison cells. The square in front of the Emir Palace entrance were frequently stained with the blood of those who were punished with death, usually cutting the throat with a knife.
Not far from the Emir Palace stands a tower with a tall column: this is what remains of the ancient Tamerlane Palace, the so-called “White Castle”. According to legend, forty courtiers rushed down from this column to catch a paper which had been snatched away from their Sovereign hands by the wind. 
Nearly 140 historic monuments of the remotest past remain standing in Bukhara, and almost each one of them has a legend or an interesting story. The fame and glory of this ancient city still attracts thousands of curious tourists from all over the world. No city has so more names than this city loved by many: Russian scientist B. Bartold said that the name “Bukhara” originated from the Sanskrit word “Bikhara” meaning “monastery”; “Bukhara-and-Sharif” (Noble Bukhara) was referred to with great respect throughout the East as a sign of admiration of the city of gifted craftsmen, architects and scientists.
The buildings of “Noble Bukhara” serve as a kind of architectural manual for architects and builders. Enter any madrassah: either the Ulugbek Madrassah, the Abdaliz-khan Madrassah, or the Kosh Madrassah and you will immediately see how crooked the corridors are. The corridors are built like this on purpose: in order for the hot air to get cold sooner, it should circulate throughout the building in an indirect way. And one more thing: each newcomer should thoroughly consider the purpose of his visit as he walks along these long corridors…