This week’s news that archaeologists have discovered the lost city of Valeriana highlights a major part of Mayan society: astronomical observatories.

More than 6,000 structures revealed themselves to a team of archaeologists who examined a 2013 ecological study in Campeche, Mexico. This part of the Yucatán Peninsula lies north of a highway on which very little investigation has been conducted until recently. Among the revelations is a privileged place for ceremonies and observation of the sun.

“Valeriana has a very busy landscape” Luke Auld-Thomasarchaeologist at Tulane University and lead author of the new research published Tuesday in the journal Antiquité, tells Inverse.

This includes a ceremonial space, consisting of a pair of buildings, with a north-south oriented platform and a pyramid to the west. Auld-Thomas says it was a place “to observe the movement of the Sun”.

Astronomical sites like this were common in Mayan society. But they weren’t all the same. Auld-Thomas said they were diverse in size and varied in terms of what they looked at, as people marked different dates of the year.

The Valeriana pyramid and viewing platform belong to a group of large structures that archaeologists call the E Group Assembly.

Archaeologists believe that Group E structures helped Mayan society create a seasonal calendar. It is likely that the structures were placed in such a way as to highlighted the positions of sunrise at the equinoxes and solstices. Monitoring celestial movements helped people meet their agricultural needs.

The observatory appeared along with other Classic Mayan structures. These include dams and reservoirs, also created so that people can survive in a harsh environment.

Their year was divided into a very dry season and a period of almost daily rain. And in the long term, the length of the wet or dry season could change significantly.

They built the structures in response to this. Archaeological evidence shows structures capable of retaining soil moisture when water was scarce. Building homes on high ground was also popular, so people could stay dry from flooding when it rained heavily.

Valeriana is important because archaeologists can compare it to other popular Mayan sites, like Chichén Itzá or Tikal. In this way, the hidden city can “provide a really wonderful natural laboratory for how a society can come up with different solutions to the same problems,” says Auld-Thomas.

Valeriana is hidden in the forest and there are probably many more buildings to discover. The observatory is located in what would have been a city center, and these areas tend to be in the middle of settlements, Auld-Thomas says. Group E structures are found in one corner of the survey area.

As archaeologists continue to explore the fascinating cultural heritage of many modern Central American communities, their responses to climate change, and their curiosity about what’s happening in the sky, the past becomes the present.