This is a semicircular construction on solid rock. The building contains two trapezium-shaped windows, which according to chroniclers originally had incrustations of precious stones and gold.

It consists of a series of buildings that overlook the Citadel area. Its semicircular foundations are placed on solid rock with a natural curvature of 10.5 meters. The stone blocks have been smoothly finished. On the north side there is a prominent door with hollowed-out jambs. On the west side of this temple, there is a rectangular patio (courtyard) with nine vaulted niches separated by projecting stone spikes.

The "Sun Temple" was originally a highly protected complex. In Inca times, only the priests and the Inca could use these temples, which otherwise remained closed and guarded. The population attended public ceremonies in open areas or Plazas in both Machu Picchu and Cusco.

The entrance to the Sun Temple was a magnificent double wooden door, which on the inside had a locking system consisting of stone rings. Two wooden bars must have been hung from the doorhead and tied into the small stone compartments carved in the inside jambs.

The whole temple was built on an enormous boulder. Its shape is semicircular. Its back wall is straight and the temple was built according to Inca architecture, placing precisely shaped stone blocks on top of each other to achieve almost imperceptible joints. The semicircular wall has two windows, one facing east and the other north. According to modern scientists, these two windows were an important "solar observatory" in Machu Picchu. The east-facing window allowed a precise measurement of the winter solstice, by the shadow cast by the central stone.

Both windows had a "false ledge" carved on the outside windowsill that obviously was used to carry the instruments used for making solar observations and measurements. In the center of the temple there is a carved stone altar used to perform different ceremonies honoring the sun. This is where animal sacrifices were performed so that the priests could "read" predictions from the shapes of their hearts, lungs and entrails (in the manner of the Roman haruspex augurs). Here also, the Inca had to drink the chicha (corn beer) together with his father, the Sun. The back wall had a window with small holes carved in it, known as the Snake Window (a name given by Bingham).

The holes are very similar to those found in the Temple of the Stars, in Cusco's Qorikancha, which according to Garcilaso were used to store treasures made of precious stones and metals. Perhaps these holes were used for the same purpose.
The temple's straight walls had trapeze-shaped niches on their interior surface, which were used to house different idols and offerings. Some authors say that originally this temple had a conical thatched roof, and call it Suntur Wasi or "The Military Tower".