Located in the main platform, the Giant Stairway opens to the sunrise of the December solstice. Measured at 25 meters long and 4.4 meters wide, this structure seems to have been purely ceremonial in function, since the stairs end abruptly partway down a hill, leading to nothing. Large boulders that rest upon the risers of the stairway become fully illuminated when the December solstice sun rises. Gary R. Ziegler and J. McKim Malville have postulated that when the boulders become illuminated, a "wak'a" is activated by its solar camaquen—a case similar to when the large stone of the Torreon at Machu Picchu becomes illuminated.