Amazonian 'Stonehenge'?

Did ancient Amazonians build a 'Stonehenge'?

Archeologists think stones possibly a prehistoric observatory

These granite blocks are among the 127 found on an Amazon hilltop.

SAO PAULO, Brazil (AP) -- A grouping of granite blocks along a grassy Amazon hilltop may be the vestiges of a centuries-old astronomical observatory -- a find archaeologists say indicates early rain forest inhabitants were more sophisticated than previously believed.

The 127 blocks, some as high as 9 feet, are spaced at regular intervals around the hill, like a crown 100 feet in diameter.

On the shortest day of the year -- December 21 -- the shadow of one of the blocks disappears when the sun is directly above it.

"It is this block's alignment with the winter solstice that leads us to believe the site was once an astronomical observatory," said Mariana Petry Cabral, an archaeologist at the Amapa State Scientific and Technical Research Institute.

"We may be also looking at the remnants of a sophisticated culture."

Anthropologists have long known that local indigenous populations were acute observers of the stars and sun.

But the discovery of a physical structure that appears to incorporate this knowledge suggests pre-Columbian Indians in the Amazon rain forest may have been more sophisticated than previously suspected.