Group G forms one of the largest clusters of major palace type construction known at Tikal. It is fronted by a spacious east-facing platform and has a broad entrance stairway. Group G is associated with the Late Classic ruler Yik'in, and it may have been his private palace quarters.
Yik'in was the son of Hasaw Chan Ka'wil, and was, if possible, an even more prodigious builder than his father. He is known to have constructed Temples IV and Temple VI, possibly the Mendez and Maler Causeways, including the giant rock sculpture attributed to him along the Maler Causeway, and Palace Structure 5D-52-1st (the Five Story Palace in the Central Acropolis).
Source: Harrison, Lords of Tikal, p. 162
"One feature of this multi-roomed structure is a vaulted interior passageway leading from the rear exterior of the building to the inner court in front of the building. The entry to this tunnel is through the mouth of a huge monster mask."
Coe, p. 93
Detail of stucco work around the supposed "monster mouth" doorway. However, I have trouble seeing a monster mouth, probably because the design has become too eroded to make out the pattern any longer.
After an abrupt right angle turn, the tunnel empties into the interior plaza area of the palace.
View from interior court toward the grand entrance.
Writing of the three palace groups of Tikal which have grouped the main buildings around a single or double courtyard, Harrison writes that "in each of these groups, the known room arrangements are complex. There are transverse rooms and rooms in tandem, sometimes interconnected, sometimes not.
In all observable cases there is evidence that the room arrangements were changed over time: big rooms were divided into smaller ones, and routes of access altered, common features of palaces."
Harrison, Lords of Tikal, p. 185
The Palace is also known as The Palace of the Vertical Columns or Palacio Acanaladuras because of the columnar pseudo-columns gracing the facade.