The Kalyan Minaret is a majestic medieval structure
that was erected in 1127-1129 by the order of Arslan-khan
of the Karakhanid
dynasty. It is the symbol of the city of Bukhara
in what is now Uzbekistan
A good-sized minaret with a wooden top had been built on the spot of the Kalyan Minaret a short time previously, but due to mistakes in the construction it soon collapsed. Arslan-khan demanded that another be built, this one taller and more extravagant than any other in the Muslim East; thus the name Kalyan, which means 'great' or 'large'. The Kalyan Minaret stands 46m (150 ft), and for a time was the tallest structure in Central Asia.
The builders tried to make sure they did not repeat any of the errors that caused the first minaret to fall; great care and patience were utilized in the construction of the Kalyan Minaret. There is a legend that says the man in charge of laying the foundation for the Kalyan Minaret, which was made from mortar and gancha (plaster) mixed with camel's milk, left the city and would not return to allow construction to continue until he was sure that the foundation had sufficiently dried...which was two years later.
The majority of the structure is composed of burnt brick and the gancha mortar, and its outside structure has 14 parallel engraved bands of unique frieze art, with Arabic inscriptions interspersed, including a band of beautiful blue and white tiled inscriptions just below the crown of the minaret.
This crown is a skylit rotunda with a number of arched glassless windows. It is reached by navigating a narrow and steep spiral staircase of brick that is enclosed between the outside wall and the inner hollow of the minaret. There are small windows intermittently spaced along what would otherwise be an uneasy ascent.
From the top of the minaret, a muzzein would call the faithful to prayer; the minaret has also been used as a watchtower and a lighthouse for trade caravans for much of its almost 900 year long history. The guard post from which the citizens were warned of impending danger (usually arriving in the form of dust storms, caused both by the weather and invading armies) still exists, and is manned by one person today. Looking out from the windows of the rotunda, the Kalyan Mosque can be marveled at, with its stunning aquamarine-tiled dome, which is reminiscent of the architectural devices that crown the Kremlin, among many other Central Asian structures.
Relatively recently, the tower gained an unsavory reputation as the 'Tower of Death'. At least one unique source reports that, starting in the 18th century, the minaret was used as an execution tower. The most depraved lawbreakers were marched to the summit of the minaret, tied up in sacks and thrown from the window to crack apart on the stone plaza below. This practice was supposedly halted in 1884. I have also read that this is merely a legend that has been exaggerated, and that the locals say only one execution was performed with the use of the Kalyan Minaret; perhaps this was what occured in 1884.
During a repair in 1924, glazed bricks covered up the frieze. The lower part of the minaret has now been restored, and most of the dust and dirt accumulated over the years has been removed.
In 1220, when Genghis Khan was leading his forces in a sweep of Central Asia, he conquered Bukhara and leveled it to the ground, but he left the Kalyan Minaret standing, because he reveled in the splendor and power of the magnificent structure, as most everyone who has ever experienced it has.
Information gathered and paraphrased from public domain text at:
These sites have mostly the same information; each site has a tidbit or two the others don't.