From the "Holy Plaza", towards the northwest is a stairway that rises conducting directly to the " Intiwatana" group, which seen from far away has the shape of an irregular interrupted pyramid that Bingham named "Sacred Hill". It is impressive how the whole sector was adapted to the shape of the natural hill. Surrounding the hill, there are many narrow terraces that are not necessarily farming ones but served in order to stop erosion and protect the "Intiwatana". Almost always those narrow terraces were also used as gardens, that is, with an ornamental purpose; they have no irrigation systems as in the farming ones (excepting the farming terraces in Machupicchu that are in a very humid area making aqueducts unnecessary). Thus, according to their duty, it is possible to identify three terrace types: farming, protective, and ornamental. Before arriving to the top of the hill, on the right side of the stairway there is a ring carved on a rock that is encrusted in the wall; it possibly served in order to support an insignia or flag kept by a spear; old accounts suggest that it was something common in platforms like this. The eastern top of the natural formation was flattened artificially in order to be used as an "Usnu", that is, a special platform from which the Machupicchu chiefs could talk to their people who were standing up on the Main Plaza located in the lower part towards the northeast. The communication was facilitated by the high location of the platform from which there is no interference, and by the sonority reached by human voice that is apparently reflected and amplified when colliding with the opposing terraces. In the central part of that "Sacred Hill" there are vestiges of finely finished buildings with their classical trapezoidal openings; around here, there is an apparently non carved natural rock that is suggested to be a vestige of a Machupicchu model; curiously, the shape of that rock has many coincidences with the local geography. By the top of the hill is the famous carved rock named as "Intiwatana", its shape is irregular (polygonal) finishing with an almost cubic polyhedron on which the top has signs of having been hit. Originally, all the faces of this boulder must have been finely polished; possibly the same way as the Main Temple in Ollantaytambo, that is, it had a smooth surface almost as glass. Moreover, it must have had other auxiliary elements for its use.