Compare the images above. The rooms now visible were buried beneath rubble cleared during excavation beginning in 1933.
When occupied, this mud and stone building would have required periodic maintenance. Once people departed, natural forces prevailed - mortar eroded, roofs collapsed, walls tumbled. What you see today is an excavated building, heavily stabilized to postpone deterioration.
The modern iron beam and plate visible here support the upper walls. The low walls exhibit Portland cement, used from the 1930s to 60s, and new stabilization mortars that more closely duplicate original materials. Although walls stand in their original location, virtually all the mortar you see is modern. Stabilization has compromised the historical architecture, but helps an excavated building withstand natural and human-induced erosion.
You are one of hundreds of thousands of visitors - please, do not lean, sit, or walk on any walls.