Herouni is sure the site is as Parsamian said, an astronomical instrument.  And he is also sure the site was used to plot sunrises, moon phases, and he adds, "the beginning of a calendar. 

To plot the sky, you have to have an idea of time. These stones—many of which look to the azimuths, were used at specific times of the year to chart solar and lunar phases.  Those with eye-holes point exactly to the point where they occur at exact times of the year.  What astonished all of us during our expedition was just how correct they still are."

Unlike star positions, the sun and moon continue to cross azimuths in the same position in the night sky.  So key stones emerged as reliable predictors of their phases.

"This would be crucial to the ancient cultures," Parsamian said about the observatory at Metsamor.  "The ancient's had to know when the new year began, the exact moment.  At Metsamor they could observe Sirius appearing in the rays of the dawning sun.  That was the cosmic event they looked for, the one they staked their reputations as priests by predicting.  This was complicated stuff."   

    And those that didn't have holes, what were they for?  "They were all part of the same instrument," Herouni says.  "Eye holes were not enough without other points to fix the angle of the sight.  So we have stones to look through, and others close by that were used to line up the stone, to establish the angle of sight." 

"There is one stone, which can be called the keystone to the whole complex, it has a bowl carved on one side.  At first I looked at that bowl and thought, 'What on earth could this be?'  Then it rained one evening, and the next day the bowl was filled with water, and I thought, 'Of course!  This is a leveling stone!'"

By pouring water into the bowl, Herouni believes the ancients could set the angle of the keystone, thereby setting the other stones into position.  An ingenious method at the time.  "You can't tell me these people were simple," Herouni challenges.  "They understood geometry and the laws of physics long before anyone in Europe began to look into the matter.  This was an incredible culture."

Herouni points out three stones (#60, 62, 63) which form part of a single instrument, "a beautiful and important instrument," he adds.  "So many of these stones look like animals or people.  # 60 we called the cock, or rooster, because of its shape.  One tip is higher than the other, and was a sighting point for #62, which has an eye-hole that looks right over its tip.  Then there is #63, which has an eye-hole that also looks at the tip of the rooster, but at a different angle.  It was the leveling stone for the first two."