"What other secrets about our past are still hidden in Brazil's jungles?" These are the musings of Lailson Camelo da Silva, the man credited with stumbling across the "Amazon's own Stonehenge," the New York Times reports. Scientists had come across the huge granite blocks—a 2006 AP report say there are 127 of them, some as high as 9 feet tall, arranged in a circle—in Amapa state along the Rego Grande waterway as far back as the late 1800s, but those explorers didn't place much significance in them. Then da Silva, an ex-ranch foreman, found them: first as a teen in the 1960s while on a hunting trip, then again in the 1990s while helping deforest the jungle. And he'd stayed away for three decades for a reason. "The place initially felt sacred, like we didn't belong here," he says, noting, however, that the site was "impossible to miss" when the trees were being taken out.
A decade or so ago, Brazilian archaeologists got money and permission to rope off the stones (also known as the Calcoene observatory) and started studying them in earnest, taking measurements during the winter solstice and applying radiocarbon dating. The experts have dated the stone structures back around 1,000 years ago and believe they were set up as an astronomical observatory. This find, combined with other physical evidence in the Amazon rainforest, appears to contradict earlier theories that the region had been "untouched by humans" in ancient times, save for tiny nomadic tribes. Some experts say more research is needed to definitively determine if these rocks were used for astronomical observations. "It takes more than a circle of standing stones to get to a Stonehenge," says an astronomy professor. (How Stonehenge may have been built.)