Platform A4 divides the Group A plaza in two. It was a later addition to Group A during the reorganisation of the group that involved the destruction of the earlier building under Platform A5. When excavated it was very poorly reserved but was able to be reliably restored. There was no earlier version of the structure; it consists of a platform with two levels that faces east towards the principal architecture of Group A. The upper level is topped with a cornice and access was via two stairways flanked by balustrades.