[citation needed] Though the stones have not been submitted to dating techniques, carbon-dating of pottery sherds has placed the site at 500 – 2000 years old.

[citation needed] On the winter solstice of December 21, the shortest day of the year in the northern hemisphere, the shadow of one of the blocks disappears when the sun is directly above it.

[2] It is this block's alignment with the December solstice that leads archaeologists to believe the site was once a type of astronomical observatory.

During the winter solstice, the sun shines directly though this hole onto another rock for an extended amount of time,[citation needed] supporting the idea that Amazon Stonehenge was used as an astronomical site.

[4][5][1] Evidence has been found near the Rego Grande site and all over the Amazon to suggest that the indigenous people of the region lived in a complex societies that involved both agriculture and a close relationship with the natural environment around them.

[citation needed] Despite not knowing the exact use of the Rego Grande site, most scientist agree that it alludes to a pre-Columbian society that was much more complex than previously thought.