Some of the buildings constructed by the Karakhanids still survive today, including the Kalyan minaret designed by Bako and built in 1127 by Mohammad Aslan Khan (r. 1102–1129).

A minaret of the Po-i-Kalyan mosque complex in Bukhara, present Uzbekistan, it is today one of the most prominent landmarks in the city.

An earlier tower collapsed before completion.

Made in the form of a circular-pillar baked brick tower, narrowing upwards, it is 45.6 meters (149.61 ft) high (forty-eight meters including the point), nine meters (29.53 ft) diameter at the bottom and six meters (19.69 ft) overhead.

The body of the minaret is topped by a rotunda with sixteen arched fenestrations, from which the muezzins summon the Muslims in the city to prayer.

There is a brick spiral staircase that twists up inside around the pillar to the rotunda. (Once the minaret was believed to have had another round section above the rotunda, but now only the cone-shaped top remains.)

The tower base has narrow ornamental strings belted across it made of bricks which are placed in both straight or diagonal fashion.

The frieze is covered with a blue glaze with inscriptions.