The structure, known as Vasca Votiva (Italian for sacred tank), was discovered in 2004.
The wooden pool reflected the sky, and people looking at it would feel like they were looking into another realm, according to the researchers.
"As you would have come up to this thing, as soon as you'd been able to start to see the surface, you would have seen effectively the edge of the land around the sky," Cornell University archaeologist Sturt Manning told Live Science. "And as you got close to it, then you would have just been looking at the [reflected] sky – so you'd have, in a sense, entered another world." Today's infinity pools are similar in their reflective beauty.
The researchers were able to use carbon dating from wooden planks to discern the age of the pool. They determined that it was built between 1436 BCE and 1428 BCE, during the Bronze Age.
This was a period of cultural change in the region. Society was transitioning from small farming communities to larger settlements, according to the researchers.
Therefore, they determined this couldn't have been used for irrigation or farming as the structure was too complex.
"If it was just for irrigation or something, then fine, but it doesn't seem to work for that," Manning said. "It's more about some group activity that they think is going to be beneficial, or that the gods are going to be pleased that they have done this."
Manning even compared it to the Neolitic Stonehenge in England, as they're both designed as if they are transporting people to another world.