Today the consensus among many scholars (among them Kim MacQuarrie) is that Pachacuti constructed it as multi-purpose residence, citadel, observatory and religious site.

[3] In this role it would support his panaca (family and descendants), provide a secluded royal retreat located well away from Cusco where he and the nobility could relax between military campaigns, undertake ritual and religious ceremonies, serve as a refuge in times of danger as well as commemorating his victories over the Cuyos.

[5][6] In addition to Pisac the other royal estates that Pachacuti is considered to have established were Ollantaytambo and Machu Picchu (conquest of the Vilcabamba Valley).

[9] In his book Squier offered the following introduction to the complex: Let us imagine a bold headland of mountain, projecting out from the great snowy masses of the Andes, an irregular oval in shape, three miles long, and at its most elevated point four thousand feet high.

It is separated by gorge and valley from the parent mountains, except at one point, where it subsides into a relatively low and narrow ridge, scarcely a hundred paces broad.

It is rough and forbidding in outline, here running up into splintered peaks, yonder presenting to the valley enormous beetling cliffs, and here and there holding open, level spaces and gentle slopes in its rocky embrace.

Two of these are on the side towards the valley of Yucay, which it was mainly designed to defend; and the third is at the narrow neck or ridge connecting it with the parent mountain.Squier's book did much to bring the complex to the attention of the English-speaking world.

The complex is divided into seven architectural areas (from north to south) - Qantus Raqay, Qallaq'asa, Inca Qonqorina, Intiwatana, P'isaqa, Hospitalniyoc and Kanchis Racay.

[9][13] These are separated by natural terrain but accessible by narrow paths wind tortuously along the ridge and in two places passing through two tunnels with running water supplied by canals.

[4] On the opposite bank of the Kitamayu River on an irregular almost vertical mountain slope is the T'antana Marka, which is home to the looted tombs of the biggest pre-Hispanic cemetery in the region.

One continues along a path along the western side of the ridge above the Kitamayu River to the Tianayoc from which via a 3-metre long tunnel is reached the Inca Qonqorina, which is an administration area.

[14] The second route drops down the eastern slope to the base of the Qallaq'asa and then continues southwards across the hillside and through a trapezoidal doorway called Amaru Punku (serpent gate, Qechua etymology) in a partial wall and then via a 16-metre long tunnel hollowed from the rock to connect with the path leading from the Tianayoc to the Intiwatana.

From the Intiwatana a path beginning at its southeast corner drops down to the P'isaqa area that has a somewhat semi-circular shape following the mountain's silhouette.

[15] This area whose name means "gold sifter" is on the ridge south of the Intiwatana is home to several towers (Pucaras) used for communication or observation and some very steep terraces probably used for defense.

[4] On the eastern slope below the Coriwayrachina in what is known as the Hospitalniyoc area are six storehouses (qullqas, also spelt as colca, collca, qolca, qollca, qollqa) of equal size and constructed of adobe.

They are often situated on hillsides and located so that they are mostly in the shade, while the higher altitude ensured that they had good ventilation and lower temperatures, which protected their perishable contents against decay.

Under-flooring and drainage canals were additional aids in keeping the interior atmosphere dry and allowed for the storage of goods such as grain and potatoes for two years or more.

The Intiwatana is housed in a semi-circular building similar to the letter "D", with one lateral straight wall which main gate is toward the south is built of perfectly fitted blocks of the finest pink granite.

The name of the Qallaq'asa residential area which is 3,514 metres (11,529 ft) above sea level comes from the Quechua words q'alla (cut) and q'asa (pass), in reference to a tunnel that connects it with the Intiwatana.

[16] Cascading down the side of the hill its 23 buildings are built from rough field stone, stuck together with adobe, indicating that they were probably inhabited by lower-status workers.

From its position overlooking the road toward the Paucartambo region and the Antisuyo and controlling the northeastern corner of the complex it probably served as the home of the military garrison or as a shelter for local villagers in times of war.

[4] Opposite the Inca baths on the other side of the gully down which the Kitamayu River flows are tombs cut into the steep cliff face of the adjacent mountain.

[15] The mountain spur is covered with approximately 500 agricultural terraces[4] called andenes, some 6 metres (20 ft) high in places, which follow the contours of the hillside.

On the eastern slope of the ridge on a path that connects the bottom area of the Qallaq'asa with the Intiwatana the Inca engineers enlarged a natural fissure in the rock to create a 16 metres (52 ft) long tunnel through the entire cliff.