The Intiwatana or "the sunīs hitching-post", is located at the top of the "Sacred Hill", formed by a number of platforms and terraces, and accessed by a 78-step stairway up to an open courtyard with finely worked walls. The Intiwatana performed two functions: measuring time (solstice and equinox) from the sun's rays, and serving as an altar.

On one of the terraces there are three steps carved out of the granite, and at the center there is a kind of carved and polished monolith, consisting of a series of flat surfaces and ending in a four-sided prism 0.36 meters in height , with a northeast - southwest orientation. Its corners point to the four points of the compass.
This stone is the center and most important part of a complex system for making astronomical measurements to determine the beginning and end of the harvest cycle, and was also apparently used as a ritual altar.
It has a polygonal shape, like an almost cubical polyhedron. There are signs that something had once been stuck to its tip. Originally, all the faces of this stone must have had a mirror-smooth finish, possibly similar to that of the Main Temple at Ollantaytambo. Also, there must have been extra items around it for its function.
The word Intiwatana, that signifies carved stones generally, was first used by George Squier in 1877, and has not been found in any ancient chronicle. The correct names for it would have been those used by the chroniclers, saywa or sukhanka. Intiwatana may be translated as "the hitching-post of the sun" or simply "the sun's clasp".

On the winter solstice (June 21), the quechuas had to celebrate the Inti Raymi, (Sun Festivity). This was the Inca culture's most important celebration. On that day, the sun is at its farthest from the Earth. For this reason, the quechuas were afraid that their "Tayta Inti, Sun Father would abandon them, and held a number of different rituals to beg the sun not to leave them, including a symbolic "hitching" or "mooring" of the sun to the Intiwatana. However, Intiwatana has another possible meaning. Since Inti means "sun" and Wata means "year", the word could also be translated as "the place where the solar year is adjusted ".

Undoubtedly, it was also used for the purpose of predicting and measuring the solstices and equinoxes (the seasons), and therefore of establishing sowing and harvesting times. A reference to this stone only as a "sundial" or something of that nature, is a mistake and shows lack of proper speculation. The Inca and Inca society had no need to measure the day in hours and minutes. The sun's height in the sky easily indicated the time of day to them as it does today to rural dwellers.

Many scholars claim that the "Intiwatana" was also a device for orientation, whose angles indicated the "magnetic" north, which would imply far greater knowledge of astronomy and physics. Astronomers Blanco, Dearborn and Mannheim declare that this astronomical complex affords an excellent observation point for the Pleiades, a very important constellation for Andean agriculture, and constellations such as the Southern Cross, Spica, Alpha Centaurus, Vega, Deneb and Altair. Local scholars point out that the Intiwatana of Machu Picchu forms an integral part of a ceque, an imaginary alignment of observatories, temples and ceremonial urban centers.