Some 3,000 years ago, the people who would come to be known as the Maya started to build the kind of monumental architecture—pyramids, plazas, and vast urban settlements—that still inspire wonder to this day.

From the very beginning, these great works included astronomically inspired complexes, known as E-Groups, that mark the rising of the Sun on key dates. For well over a millennium, E-Groups proliferated across central America and embodied a diversity of configurations, fit to the customs of the cities that still stand today in lush archaeological sites like Tikal, El Mirador, Uaxactún, Seibal, Cival, and Yaxha.  

Most E-Groups feature a large pyramid located at the west side of a plaza, which faces a raised platform on the east side with three points, usually marked by temples, along a north-south axis (there are also variations that place pyramids at the southern or northern side of the plaza). From the vantage point of the pyramid, the Sun rises behind the central temple to mark seasonal moments, like the onset of the dry or rainy seasons, or the solstices. In some cases, observers also viewed sunsets behind the western pyramid from the central temple of the eastern platform.

The complexes can vary widely in styles and dimensions, but all E-Groups appear to have played a complex role in political, social, and ritual life for the Maya. Debates have raged for a century among archaeologists about the significance of these captivating constructions. How foundational were they to the origins of Maya civilization? Should they be considered ancient astronomical observatories? And what role do they play for modern Maya people who aim to embrace and revive the traditions of their ancestors? 

“Wherever E-Groups were excavated, the differences in archaeological contexts suggest that their primary uses and aspects of the associated symbolism were not always and everywhere the same,” said Ivan Šprajc, a professor of archaeology at the Research Center of the Slovenian Academy of Sciences and Arts and an expert on the Maya, in an email to Supercluster. 

“They served for politically important agricultural and other rituals, royal ascension ceremonies, elite burials, ancestor veneration, sometimes perhaps even as marketplaces,” he added. “Only further excavations may shed further light on regional and time-dependent variations.” 

In 1924, the Danish archaeologist Frans Blom introduced E-Groups into modern history during excavations at Uaxactún, a sacred Maya site in Guatemala that dates back about 2,500 years. Excavators had labeled an iconic structure “Group E” in their map of ancient Uaxactún, which is how these assemblages ended up with the generalized name “E-Groups.”

In the century since Blom’s discovery, dozens of other E-Groups have been found across the remains of this influential empire, mainly clustered in the Maya lowlands of Mexico, Guatemala, and Belize. Now, as Mesoamerican archaeology flourishes due to increased investment and innovations like the remote-sensing tool LiDAR, researchers are pushing back the timeline of these idiosyncratic structures to the genesis of Maya urban civilization itself.

For instance, in 2020, archaeologists led by Takeshi Inomata discovered the oldest known Maya ceremonial site using LiDAR. The huge complex, called Aguada Fénix, located in Tabasco, Mexico, and dates back to about 1100 BCE. The site contains an expansive primordial version of an E-Group set on a platform that is nearly a mile long, demonstrating that these structures are an original feature of Maya architecture.

The E-Group at Aguada Fénix is “the oldest so far,” said Francisco Estrada Belli, a Maya archaeologist and research professor at Tulane University, in a call with Supercluster. “But it's like the other ones, with a western pyramid and a long platform on the eastern horizon. In those days, they didn't actually put temples at the three intervals; they just used the edges of the platform and the centerpoint.”

Estrada Belli believes that the deep origins of E-Groups suggests that they are core to Maya identity. He has spent years untangling the mysteries of Maya sites—especially at Cival, a 2,000-year-old city in Guatemala—and considers the construction and consecration of these complexes as a representation of a city’s birth.

“The very first offerings that [the Maya] laid out in the plaza are foundational-type offerings,” Estrada Belli explained. “There are rituals that represent the type of offering that you give to the universe when you want to found a new sacred space.” 

“I argue that this wasn't just any offering,” he continued. “It corresponds to the foundation of the city. The city itself did not exist until there was this central plaza we now call the E-Group that was dedicated to celebrate the sunrise and the cycles and all the deities related to it. It really marks the identity of Maya people as we know it today. It’s the first material manifestation of those beliefs and it’s the earliest manifestation we have of their civilization as such.”

In this way, the E-Groups are an important emblem of the origins and early rise of Maya culture, during the Preclassic and Early Classic periods that span about 1000 BCE to 900 CE. However, their salience began to fade away over the centuries and the Maya had shifted focus to other forms of architecture long before the arrival of Europeans in the Americas.

“While important in early periods, E-Groups were not the main feature of Maya civilization,” Šprajc said. “With only a few exceptions, they were not built after about 600 CE. They were popular during the Preclassic and Early Classic periods, but even along this time, as the architecture became more diversified, other types of complexes appeared, adopting the earlier functions (including astronomical) of E-Groups.”

In other words, E-Groups were an important urban template, but Maya civilization branched off into too many dazzling new directions to be wholly encapsulated by them. Still, during their heyday, E-Groups embodied a wide variety of purposes for Maya settlements, and the roles they had pioneered were sometimes fulfilled by other architectural creations. 

On a practical level, E-Groups provided guidance about agricultural timelines for planting and harvesting. They were ceremonial grounds where kings became the corporeal representation of the universe. They offered a space for public commons, sports, and administrative functions. But there’s one question that has been debated since Blom first described these complexes 100 years ago:

In his writings, Blom marveled at the astronomical sophistication of Uaxactún’s E-Group, which he interpreted as marking the summer solstice on the north temple, the vernal equinox at the central temple, and the winter solstice on the south temple. He proposed that this complex was a “solar observatory,” a concept that exhilarated academics and the public, as it reinforced the keen celestial knowledge of this ancient culture to a wide Western audience.  

A century later, archaeologists have largely rejected the idea that the Maya observed equinoxes; the central temple more likely marked a so-called “quarter day” in the Maya calendar linked to the onset of the rainy season, which happens to fall close to the spring equinox. Still, Blom’s interpretation of these complexes as astronomical observatories remains mainstream, despite the efforts of many scholars who have challenged it over the decades.

Šprajc, for instance, argued in a 2021 study that “an ‘observatory,’ in the modern sense of the word, is a place to acquire knowledge” whereas “astronomically oriented Maya buildings represent, rather, the results of knowledge.”

In other words, our modern understanding of an “astronomical observatory” is a place to collect data about phenomena in space. The Maya, in contrast, would have seen E-Groups as constructions that, though inspired by astronomy, were designed to impose cosmic order and thereby influence events on Earth, and not overtly as a means to produce new insights about stars, planets, or other celestial phenomena. 

“That is why I believe the term cannot apply to the ancient astronomically oriented structures,” explained Šprajc over email. “Most of the publicly important Mesoamerican buildings (temples, palaces), not only E-Groups, were oriented on astronomical grounds. Therefore, the orientation was only one of the criteria dictating the design of these structures. Since their primary functions were religious, residential, funerary, or administrative, they cannot be defined as observatories.” 

“They did serve for monitoring celestial events and may have sometimes even produced new insights,” he added. “However, in order to discover the regularities of celestial phenomena, it was not necessary to build elaborate monumental structures.”

Indeed, the Maya who built the first monumental structures at places like Aguada Fénix had likely used mountains, and other landmarks, as astronomical and calendrical guides for many centuries. 

E-Groups arose as a material manifestation of observations and calculations that had been based on topographical features and were passed along for untold generations. This deep tradition of Maya skywatching is one reason that Estrada Belli prefers a looser interpretation of the word “observatory” than others in his field. 

“People focus on whether it is an observatory, and I think that's besides the point,” Estrada Belli said. “It really depends on what your definition of ‘observatory’ is. The modern definition of an astronomical observatory is a place where you have a telescope and a lot of instrumentation. But an observatory could be any place that could be used to observe the sky.”

The Maya “were definitely looking at the rituals that were performed by the kings in these plazas, but the focus is the sky, so in a way, [observatory] is not a complete misnomer,” he added. “But obviously they already knew everything about the sky before they started building these things. Presumably, these concepts go back to a time before there was architecture. Any part of the landscape could have been an observatory before Maya civilization.”

Many other Maya scholars have commented on the relevance of the term “observatory” as a descriptor for E-Groups. Overall, the word seems to have been fading in academic papers on this topic in recent years. However, Šprajc doesn’t expect a new consensus to emerge overnight.

“Since the idea that E-Groups were intended to record the equinoxes and the solstices is based on such an interpretation of Group E of Uaxactún and was published back in the 1920s, the ‘observatory’ opinion became very widespread,” he said. “I am thus sure that it will take quite some time to change this general opinion (visible also, for example, in many explanatory tables at archaeological sites).”

For over a millennium, Maya E-Groups served as calendric devices, hallowed grounds, and a stage for the Sun on Earth. Now, modern Maya, the living descendants of this ancient civilization, are returning to these sacred spaces and reviving the traditions of their ancestors.

“They are making rituals to the places that were occupied at the time of the conquest” by Europeans, said Estrada Belli. “They go back to these cities that have been in ruins for 500 years, and they're trying to reclaim them after 500 years of colonization and oppression, and trying to be converted into Catholicism. Now they're going back and performing modern day rituals, which are very much a reflection of the ancient rituals.”

“Not only do they claim the places where they're directly connected to, in terms of their community in the highlands and the Yucatán, but they're also going back to the places that were abandoned 1,000 years ago,” he added.

As archaeologists continue to unravel the mysteries of E-Groups, uncovering their ancient role in tracking the Sun and structuring Maya life, it seems the story of these sites is far from over. Modern Maya may reinvent these spaces in ways that blend ancestral knowledge with contemporary spiritual and cultural expressions. Just as the past shaped the present, the present may redefine the past by demonstrating that E-Groups are not dead relics but living sites of meaning, adaptation, and renewal.