It is thought that these underground rooms housed the slaves. In the Middle Ages, the rooms were filled with materials moved out of the way to build the palace apartments. Cleared out in 1956, they revealed amazingly thick walls and lovely vaulted ceilings. Their location has enabled experts to imagine the layout of the imperial apartments above. The central section leads from the Bronze Gate to the palace peristyle. Today it is the scene of arts and crafts stalls.