The Ancient Peruvian Fortress of Cerro Baúl

In an area to the far south in Peru, just north of the Atacama Desert, lie the ruins of Cerro Baúl, an ancient political outpost and ceremonial center settlement in Peru occupied by the pre-Incan empire called the Wari, a powerful culture which began in the early AD period. The terraced mountain is 2,000 feet above its surroundings, with a settlement on the cliff tops themselves and in the immediate surroundings, a prominent stronghold that was the southernmost outpost of the Wari, one of the great empires of the Andes.

Cerro Baúl sits atop a high mesa in southern Peru

Archaeologists discovered Cerro Baúl in the early 1980s and conducted preliminary excavations in 1989. Extensive investigations have been underway for the past five years at this site that sits about 250 miles south of Cuzco. In early July, Dr. Ryan Williams, an anthropological archaeologist who works on the earliest expansionist states of South America, and his colleagues from the Field Museum and the University of Florida, discovered more than 20 preparation vats and the remains of what were once open-hearth fire pits. In the fire pits, hot-burning llama and guinea pig dung, along with other refuse from the settlement, were used to boil water and other ingredients to make chicha. These fire pits revealed ash and broken shards of the large ceramic preparation vats, which held 10-15 gallons.
    Also discovered was at the center of this mountain fortress was the plaza of the sacred stone, an architectural compound built around a large boulder at the center of the summit. Sacred stones were prominent features of Peruvian cosmology, and a similar structure has been uncovered near the Wari site of Pikillacta in the Cuzco region. These stones were the centers of ritual and received offerings of special libations or of sacred items.
    The most common architectural form at the capital and other early cities in Peru was an enclosed plaza flanked by impressive stone halls. These halls included residences of governors and wealthy citizens, government offices, and houses for state-held parties that rewarded the loyalty of important subjects. The most interesting of the long halls that have been excavated so far contained a burnt deposit of classic vessels and keros, some of which were decorated in a hybrid Wari-Tiwanaku style. Six fine necklaces were also recovered from this burnt offering. Each had an average of 970 shell beads, some with a few lapis lazuli or chrysocolla tube beads as well. The evidence suggests the fire that destroyed the hall was intentionally set, and the beautiful ceramic vessels, many of them probably brought more than 500 miles from the Wari capital, were deliberately smashed and thrown into the smoldering flames.

Ruins of Cerro Baúl atop the high mesa

Within these remnants of large buildings that were likely used for ceremonial purposes, there is evidence of damage that has been interpreted as a careful and deliberate destruction, by the city's own people, of several buildings prior to the evacuation of the mesa. The summit of the mountain is located in the Moquegua Valley, and adjacent to Cerro Mejia. Moquegua is a department in southern Peru that extends from the coast to the highlands.
    The summit of Cerro Baúl can be divided into western, central, and eastern areas, and has remains of large masonry buildings in all areas, including ruins of conjoined, multistory monumental architecture concentrated in the central and more particularly in the eastern summit area. Other than a low rectangular platform mound (the only such structure at the site) and some associated terraces in the west, and occasional out-buildings in the west-central area, these other summit regions were little developed and have scant occupational refuse.
    However, the eastern focus—the area overlooks the sole route of access and the perimeter architecture, now slumped, were defensive, and the structures were built of stone quarried from the rock cap of Cerro Baúl itself, though silt-rich mortar had to be carried up from the irrigated valley below, as did the water used in mixing the mortar.
    It is obvious to those who have studied the site that both hill-top summits were clearly built for defense. Some 20 “pitted stone piles” dot the land below and were non-defensive buildings on the flats that were destroyed in antiquity—in fact, it was so complete that no wall, foundation, floor or other architectural elements remained intact.
    In fact, the chronicler Garcilaso de la Vega described the mesa as an impregnable natural fortress where local forces defied conquest. The strategic nature of Cerro Baúl is evident in the elaborate fortifications controlling the sole route to the summit. The imperial character of the complex is evident in its spread of more than 10 ha of monumental masonry architecture (William Harris Isbell and Gordon F. McEwan, Huari Administrative Structure: Prehistoric Monumental Architecture and State Government, Dumbarton Oaks Trustees for Harvard University, 1991, pp131-132).

The long, difficult climb to the top of Cerro Baúl

In addition, the summit of Cerro Baúl is divided into two areas of very different architecture. A monumental core comprises one- and two-story masonry buildings, while the eastern occupation, extending to the edge of the mesa and overlooking the route of ascent, is crowded with more modest, one-story stone dwellings similar to those found on the terraces of the slopes.
    Building atop the mesa was a daunting task. Earth for mortar and silt for plaster came from the banks of the Rio Torata, two hours away by foot. Water for mixing those materials was hauled uphill from the El Paso canal. For construction stone, Wari builders turned to the mesa itself, quarrying the western half of the summit so heavily that it resembles a cratered lunar landscape.
    Fine masonry construction was restricted to important buildings that adhered to the strict architectural canons of the imperial capital at Ayacucho. D-shaped structures are among the rarest and most distinctive buildings at the political nexus, where they likely were at the sacred center of Wari culture, an area of sacrifice and propitiation of the gods. At Cerro Baúl, we find at least one and possibly two of these temples, in which several fine artifacts were found in a ritual offering. These include entire polychrome ceramic vessels, an engraved gourd bowl, and a silver-alloy foil camelid about an inch across.
    When the Wari arrived in the valley, they introduced an agricultural technology of terracing steep slopes and digging long, serpentine canals across the broken land. A 6.2-mile canal wound from the Torata River through the El Paso Divide between Cerro Baúl and Cerro Mejia, where the water course split to irrigate expansive terraces that stair-stepped the flanks of both hills. This high-country irrigation system may be the key to the Wari's successful expansion into the extremely arid Moquegua Sierra, especially during severe droughts.
    Along these terraced slopes were the homes of the majority of the center's citizens, situated beneath the impregnable fortress high atop the mesa that, with its sheer walls and single, tortuous route to the top, the citadel defied attack by force (Donna J. Nash and Patrick R. Williams, "Architecture and Power on the Wari–Tiwanaku Frontier,” Archeological Papers of the American Anthropological Association, vol 14, 2004, pp151–174; also see Empire of the Andes).
    The adjacent Cerro Mejia, which is more than two square miles in area, shows remains of large buildings, many of them houses, scattered across the summit, which is ringed with boundary walls. The southern slope, facing Cerro Baúl, is divided by large walls into several neighborhoods and each neighborhood has eight to 15 houses built on terraces. The lower portion of Mejía's southern slope was used to grow crops, these fields were watered by a canal, which also supplied the settlement with potable water since it is located away from the river.
    The term Cerro Baúl means “hill trunk,” or a place where treasure is kept. Whether or not any treasure was kept there, it was a magnificent hilltop fortress that was completely impregnable and impossible to overcome force. It obviously guarded the entrance to the north and directly into Cuzco.