The Kosh-Madrassah complex consists of two madrassahs. Twenty-three years after the completion of Modari-Khan Madrassah in 1590 there was built Abdullakhan Madrassah. Its facade virtually resembles facade of Modari-Khan Madrassah standing across the street; only its huge peshtak portal towers over the surrounding structures. The portal and the corner guldasta towers are richly decorated with intricate geometrical patterns, the loggias are bordered with a wide patterned band, accentuating horizontal and vertical divisions of the wall. But what really distinguishes Abdullakhan Madrassah among other similar structures in Central Asia is the extremely complex and varied lay-out of its interior premises.
The fretted doors lead into an entrance hall with a mosque on the right and a classroom on the left, whereas two passages open to the yard. The mosque layout is inconsistent with the axis of the whole construction: it is turned at an angle thus letting the mikhrab prayer niche be directed precisely westward. Still remaining is the covering of the mosque and the classroom with intersecting arches, stalactite filled pendentives, and the dome decorated with rather complex star-shaped girihgeometrical pattern.
Two-storied gallery of hujra cells and service premises surround the yard with four ayvan platforms. The northern ayvan has an adjoining extension with eight small rooms, sticking out beyond the facade line. Through a door in the western ayvan,opposite the main entrance, you can get into the most noteworthy part of Abdullakhan Madrassah. It is a system of cranked passages that lead into a large octahedral hall surrounded by 20 hujra cells arranged in two tiers. The dome looks soaring on the dodecahedral drum with window openings. This hall is known as Fanusi Abdullakhan (‘Abdullakhan’s Lantern’).
The great skills of the unknown medieval architect are vividly demonstrated in the soft and even lighting, the large amount of air so refreshing in hot summers, the way this hall is connected with the other parts of the madrassah… Structural parts gradually transform into ornamental decoration thus imparting originality to this wonderful structure and strengthening its impressiveness.
Abdullakhan Madrassah is one of the most outstanding monuments of Central Asian medieval architecture in which the daring attempt to deviate from canonical schemes gave rise to new architectural forms.