A thousand years ago, there wouldn't have been much jungle here, just terraced plots of maize and clear view off the mountain slopes to the valley far below. Visitors got a dizzying look at the drop from either side of a cobblestone road that lurched upward along the back of a steep ridge. At the edge of town, they'd find themselves funneled into a stairway shadowed on either side by stone walls and tall guard houses. Up the steps, a cobble-paved causeway stretched ahead, rising gradually, its edges lined with sculptures and the piked heads of conquered enemies. At the end, the chiefs' house stood on a tall stone foundation, its conical roof mirrored by the peak of the volcano in the distance.
The modern entrance to the ancient city of Guayabo is not nearly so dramatic. There's a pockmarked gravel road up a mountain, with chasms that threaten to swallow the front wheel of our boxy, little Honda. A wooden ticket booth, like a lemonade stand, marks the spot were you park the car on the roadside. Carefully maintained nature trails wind through rainforest less than a century old—this land was a dairy farm not so very long ago—and spit you out in the center of what was once a city of several thousand inhabitants.
Guayabo—pronounce it "Why-ahbo"—is one of many ancient cities in eastern and central Costa Rica that get overlooked by the general public, largely because their builders worked mostly with materials—wood, thatch, cane—that disintegrated in the tropical climate. The massive communal houses rotted away long ago. But the stone foundations, roads, tombs and aqueduct systems that remain are, in themselves, impressive enough to be named an International Historic Civil Engineering Landmark by the American Society of Civil Engineers.
I travelled to Guayabo—about two-and-a-half hours east of the Costa Rican capital of San Jose—with Michael Snarskis, Ph.D., an archaeologist who has spent his career living and working in Costa Rica.
Although Guayabo had been known (and looted) since the 1800s, true archaeology didn't begin there until the late 1960s. When Snarskis first visited the site in the 1970s, it was still mostly cow pasture. Today, though, the central part of the city has been cleared and a stretch of the main entry road painstakingly restored. At the city's heart is a piece of urban design that Snarskis said was as common to ancient Costa Rica as the grid-with-a-park-in-the-center is to small-town America.
Diorama showing what the center of Guayabo probably looked like during its heyday.
Around what Snarskis calls the "elite precinct"—think of it as Guayabo's gated community—are other, lower house mounds, plazas and pathways and the stone rings that once formed the foundations of commoners' houses.
"You had the main road that led into the city and ended at the stairway of the chiefs' house, after passing through a sunken plaza. The plaza is quite a bit lower actually, because it's the pit left behind by digging earth fill for the principal mounds. The caciques, Spanish for chiefs, would all have lived in the house on the tallest mound. And the adjacent secondary mound would have been for the wives and female slaves who took care of their domestic maintenance. The Spanish, when they first arrived, actually described this same basic design and the division of residence by sex at other places in Costa Rica, though they never made it to Guayabo," Snarskis said.
Standing there today, the city seems too small to have packed in a peak population of several thousand, but, Snarskis points out, you have to remember that only 1/4 to a 1/3 of Guayabo is visible. The jungle on all sides is littered with house foundations and tombs, which have never been fully excavated. In a way, most of Guayabo is still a lost city, waiting to be discovered.
Open tomb in the jungle surrounding Guayabo. The walls, floor and lids of these tombs were made from lajas—slabs of volcanic flagstone.
This still-buried ring of stones marks the foundation of a small house.
All the remains are stone: Either car tire-sized river cobbles hauled up from far-flung valleys or massive lajas—slabs of volcanic flagstone, some as long as a human body. Simply getting these rocks to the city is a big deal. Snarskis said the river cobbles were probably hauled up the mountain one-by-one in slings thrown over the backs of workers and slaves. The flagstones would have been even more difficult to pry out of the ground and move—remember, there weren't any pack animals around to help out.
Some of the principal mounds.
The chiefs' house. Multiple male elites would have lived here. Snarskis thinks the grassy plaza at the base of the steps may have once been a reflecting pool that's now filled with silt.
The work that went into building Guayabo isn't just impressive, it's also important, because it proves the existence of a fairly complex political system. Leaders need a sophisticated power structure backing them up to get monuments like this built. Without it, orders like, "Hey, I really think you should carry that 200-pound rock uphill for several miles," tend to get ignored. No ancient Chibchan calendars or writing systems have been preserved, but Guayabo and its sister cities weren't the work of cultural pushovers.
A carved stone, about the size of a large coffee table, found near Guayabo's center. Snarskis said that this side depicts a very stylized version of an alligator.
The other side, he said, shows a picture of an upside-down jaguar.
Nor were the Chibchan people technologically deficient—in fact, they were excellent engineers. Guayabo sits between two streams, which the ancient inhabitants tapped to bring fresh water into the city center. Aqueducts criss-cross the city, both in exposed stone-lined trenches and under the cobblestone-paved streets, carrying water to collecting pools. Some of these have been running continuously since they were built a millennium ago.
"In fact, the entire site is tilted slightly, and that's on purpose," Snarskis said. "It ensured the constant flow and circulation of water from the stream at higher elevation, through the city, and out the stream at lower elevation."
An aqueduct brings water from a nearby stream to fill this pool.
An aqueduct flows below this street, taking water from the pool in the previous shot, to another one at slightly lower elevation.
So far, Guayabo is the only ancient city in Costa Rica open to tourists. But there are others out there. At one time, they were probably connected by networks of roads. Less than 50 miles north of Guayabo, archaeologist John Hoopes, Ph.D., is currently digging at a similar city. He compares the ancient Caribbean to the ancient Mediterranean—two similarly sized seas, ringed by a host of cultures that were all individually unique, but constantly in contact, each trading ideas and incorporating foreign elements into their own, distinct style. The Maya may have been Central America's answer to the ancient Greeks, but that doesn't mean Chibchan culture wasn't also important. The more we learn about sites like Guayabo, the more we'll understand about the ancient Costa Ricans and how they contributed to the overall Caribbean cultural network.
Michael Snarskis offers guided tours of Costa Rica's National Museum, Jade Museum, Gold Museum and the ancient city of Guayabo. If you'll be visiting Costa Rica and you're interested in archaeology, you can contact him by email or by phone at 011-506-2235-8824.
Maggie Koerth-Baker is the science editor at BoingBoing.net. She writes a monthly column for The New York Times Magazine and is the author of Before the Lights Go Out, a book about electricity, infrastructure, and the future of energy. You can find Maggie on Twitter and Facebook.