It takes roughly an hour to drive from Khiva to Biruniy and a further hour to get to Ayaz

Ruins of the excavations of the palace below Ayaz qala 2, showing its complex arrangement.

Another unusual feature is the 50 metre-long sloping man-made staircase that rises up to the entrance of the fort on the southern side. At the foot of the ramp are the remains of a large square building, which is thought to have been a palace. It contained residential quarters along with numerous ceremonial halls with ceilings supported by multiple columns, one of which seems to have been a fire temple. It was lavishly decorated with wall paintings and must have been the residence of an important and wealthy feudal lord, loyal to the Khorezmian throne. 

Reconstruction of the palace showing the numerous hyperstyle halls.
From Nerazik, E. E., "In the Lower Reaches of the Oxus and Jaksartes", page 71, Moscow, 2000.

The palace was built in the 4th century AD but was destroyed at a later date by two separate fires. Given the palace's location one wonders if there was an associated defensive building on the conical hill predating Ayaz qala 2. The palace seems to have been re-used as a domestic dwelling during the 6th to 7th centuries, possibly by the same feudal family who built the fortress.