Group G lies just south of the Mendez Causeway . The complex dates to the Late Classic and consists of palace @-@ type structures and is one of the largest groups of its type at Tikal . It has two stories but most of the rooms are on the lower floor , a total of 29 vaulted chambers . The remains of two further chambers belong to the upper storey . One of the entrances to the group was framed by a gigantic mask .