The Mundo Perdido (Spanish for "Lost World") is the largest ceremonial complex dating from the Preclassic period at the ancient Maya city of Tikal, in the Petén Department of northern Guatemala.

[9] Evidence recovered from the Mundo Perdido dates back to the earliest years of occupation at Tikal in the Middle Preclassic prior to 700 BC, although these remains represent rubbish rather than structures.

[10] The complex began to take form around the end of the Middle Preclassic, around 600 BC, when structures started to be added to a series of artificially levelled surfaces or platforms.

[13] Around AD 250, at the beginning of the Early Classic, the Mundo Perdido plaza was expanded westwards in order to make the Lost World Pyramid the centre of the complex rather than the western extreme.

[11] It was this construction phase that led to the Mundo Perdido achieving its final surface area of around 60,000 square metres (650,000 sq ft).

[17] With the entry of Siyaj K'ak' and the establishment of a new political order in the city, the focus of royal funerary rites was shifted from the Mundo Perdido to the North Acropolis.

[21] The final version of the Talud-Tablero Temple received three elite status burials, possibly members of the royal family to judge by the extremely high quality of the associated offerings.

[21] The greatest residential activity during the Terminal Classic took place in the vaulted palace immediately to the east of the Talud-Tablero Temple (Structures 5C-45 through to 5C-47).

[26] Ritual activity also continued, and the bottom half of Early Classic Stela 39 was placed in Temple 5D-86 on the East Platform and worshipped.

[26] That a large population remained in residence in the north sector of Mundo Perdido during the Terminal Classic is evidenced by the quantity of burials of differing gender and age.

[26] The occupation of the Mundo Perdido came to an end in the Terminal Classic and very few traces of Postclassic activity have been recovered, limited to a few ceramic finds in Structure 3D-43 to the north.

[27] The University of Pennsylvania carried out exploratory investigations of the Lost World Pyramid prior to the work undertaken by the Proyecto Nacional Tikal.

[28] Exploratory tunnels excavated up to 27 metres (89 ft) into the pyramid's interior recovered surprisingly early ceramic fragments, which led to the complex becoming the focus of later investigations.

[32] Over the course of Tikal's history the E-Group underwent seven distinct construction phases, with the earliest dating to the end of the Middle Preclassic period.

[11] This structure was one of the most massive buildings in the whole of Late Preclassic Mesoamerica and its construction used masonry blocks that measured over 1.8 metres (5.9 ft) long.

They were not built directly centred upon the preceding version due to the necessity of maintaining the E-Group plaza area between the pyramid and the East Platform.

[39] The earliest version of the pyramid was built at the end of the Middle Preclassic;[33] it was raised upon a 1.42-metre (4.7 ft) deep infill that levelled the natural terrain.

[46] Once again it was a radial pyramid with auxiliary stairways; the temple had at least eight stepped levels although archaeologists could not determine the exact number due to the destruction wrought upon the summit by the construction of the next (fifth and final) version.

[46] Due to the method of construction employed, with weight dispersed across the shorter sides of its stone blocks, the fourth version of the pyramid was structurally weak and it required periodic reinforcement.

[50] Large quantities of Early and Late Classic ceramic fragments were found upon the pyramid, demonstrating the continued importance of the structure within Tikal as a whole.

[56] Iconographic analysis of these two masks suggest that they are an early form of Nu B'alam Chac, a spirit protector of the city that was closely associated with warfare.

[20] This version of the structure had a four-level platform with an access stairway interrupted by a vaulted niche, as was the architectural style prevalent at Tikal during this time.

[58] The Talud-Tablero Temple was not investigated by the University of Pennsylvania and prior to its exploration by the Proyecto Nacional Tikal the summit shrine had served as the lair of a jaguar and was littered with the remains of its prey.

[58] This resulted in a base height of 16.4 metres (54 ft);[67] a new summit shrine was built upon this, possessing three vaulted rooms and an elaborate roof comb.

[21] The offerings include polychrome ceramics and objects crafted from shell, conch and mother of pearl that are inscribed with anthropomorphic and zoomorphic imagery.

[14] The monument is sculpted on the front and back faces and was deliberately broken in ancient times and was moved inside the temple in order to save it.

[14] The front of the stela shows the bottom half of a person, who is identified as a ruler by his costume;[71] the back features two columns of hieroglyphs.

[73] The stela was possibly moved to the temple by king Yax Nuun Ayiin II to celebrate the changing of the 20-year k'atun Maya calendrical cycle in AD 771 and thereby link himself to Chak Tok Ich'aak I.

He was buried near the surface lying on his side in a flexed position; The remains were oriented north–south and date to the Terminal Classic and were not accompanied by any funerary offering.

The remains are those of a young adult male between 21 and 35 years old who was laid on his right hand side in a flexed position with an east–west orientation, with the head lying to the west.