Sylvanus G. Morley referred to the river cut through the Acro­polis at Copan, Honduras, as “the largest archaeological cross-section in the world” (The Ancient Maya 1948:324). Although perhaps overstated, these words certainly convey the magnitude of this fea­ture, known simply as the cortex (or “cut”). The cortex is the result of centuries of erosion by the Rio Copan which has removed the east­ern side of the Acropolis, exposing an accumulation of buildings mea­suring some 275 m wide north-south, and some 40 m high (Fig. 1). Al­though the cortex has been known to the outside world for at least 150 years, until recently it has received scant attention. Now, thanks to a major excavation program spon­sored by the American Section of The University Museum, the unique potential of the cortex as a ready-made window for documenting the function and growth of the entire Copan Acropolis is being realized.

Copan is a UNESCO World Heri­tage site justly famous for its archi­tecture, sculpture, and spectacular setting. The ruins of this ancient Maya city are in a lush tropical valley in western Honduras (Figs. 2,3) that was occupied by sedentary agriculturalists as early as ca. 1000 B.C. The culmination of this occupa­tion was during the Maya Classic period (ca. A.D. 250-900), when Copan became the political, econo­mic, social, and ideological capital of a lowland Maya city-state. Co-pan’s inscriptions provide a historical record of the royal dynasty that ruled from this capital, chronicling a roster of at least 16 kings who held power between ca. A.D. 400 and 800 (Figs. 4,5).

The focus of Copán’s develop­ment, as represented by both the archaeological and historical record, was the Acropolis—one of the largest architectural complexes in the Maya area and the center of power for the Classic polity for some 400 years (Fig. 7). Here were the palaces, temples, and administrative build­ings used by Copán’s rulers and their immediate kin. Typical of most ancient Maya monumental construc­tion, the Acropolis consists of an accumulation of superimposed build­ings. As structures were terminated, their supporting platforms were buried, building roofs removed, and rooms.

Earlier Work with the Corte

The cortex was reported to the outside world by Copán’s first ex­plorers and investigators, John Lloyd Stephens, Frederick Catherwood, and Juan Galindo, in the first half of the 19th century. It was mapped and photographed by Alfred P. Maudslay, the indefatigable pioneer of Maya archaeology, at the end of the same century. Maudslay also des­cribed the cortex in his report on Maya sites and monuments (pub­lished from 1889 to 1902), but mis­interpreted its significance, seeing the exposed plaster floors and ma­sonry walls as “foundations” for the visible buildings of the Acropolis. John Owens seems to have been the first to have recognized the impor­tance of the cortex as exposing the sequence of earlier buildings under­neath the temples and palaces on the surface. (Owens was a staff member of the expedition to Copan sent by the Peabody Museum of Harvard University at the turn of the cen­tury.) From that point on, archae­ologists have realized that the Copan cortex provides a cross-section of the architectural history of the Acro­polis. Nonetheless, for a long time the sheer size of the exposure seems to have inhibited any attempt to take advantage of it.

But if archaeologists ignored the carte, the Rio Copan did not. Two major temples originally towered above the river along the very east­ern edge of the Acropolis. Called Structures 20 and 21, they were photographed and mapped by both Maudslay and the Peabody expedi­tion. But soon after the Peabody team left Copan, a great flood under­cut the eastern bases of both struc­tures and they collapsed into the swirling river. The prevention of further destruction became a prior­ity for the next investigation at Copan, conducted by the Carnegie Institution of Washington during the 1930s. Thanks to this work the course of the Rio Copan was diverted and the Acropolis has been spared fur­ther damage.

During the Carnegie investigation, Edwin M. Shook prepared the first scaled section drawing of the carte. The energies of the other archae­ologists, however, were dedicated to excavating and restoring structures belonging to the final stage of Acro­polis construction, including two of the largest buildings and the famous Hieroglyphic Stairway containing the longest text in the entire Maya area, and nothing more was done to gain information from the carte.

Origins of Current Research of the Cortex

The modern era of archaeological research at Copan began in 1975. In that year, Gordon R. Willey of the Peabody Museum (Harvard) pro­posed to conduct a comprehensive settlement survey of the Copan val­ley. This resulted in the first assessments of the size and character of the ancient population at Copan. Although the focus of Wiley’s own investigation was on mapping and test excavations in the surrounding valley, the proposal he made to the Institute Hondureno de Antropología e Historian for archaeological research at Copan was a comprehensive and long-term plan that included investigation of the entire site by excavation, as well as pro­visions for establishing a research center and for the preservation and protection of the ruins for future generations.

At this time, the senior author of this article was excavating with his colleague, William R. Coe, at the neighboring site of Quirigná, Guate­mala. Recognizing that we would be in the field at the same time, the Harvard and University of Pennsyl­vania projects had discussed ways and means of cooperating and shar­ing data. In early 1975, as discussions on cooperation between the two projects continued, Coe and Sharer joined Willey in Copan to assist in drafting plans for research in the Acropolis. One feature of the re­sulting plan was a comprehensive investigation of the carte, including a thorough recording of the archi­tectural stratigraphy, tunneling ex­cavations to expose and record earlier levels of construction, and consolidation of the carte face to guard against collapse and further destruction. Trampling through the dry bed of the Rio Copan in 1975, Sharer never dreamed that he and The University Museum’s American Section would one day find them­selves in the midst of a multi-year program aimed at carrying out that investigation.

The University Museum’s Corte Excavation

In 1978, the first attempt to realize the plans for a cortex investigation was made. George Guillemin, an experienced field archaeologist who had previously worked for Penn’s Tikal project, excavated three tun­nels that extended from the corte deep beneath the Acropolis East Court. Tragically, Guillemin died shortly thereafter, and his tunnels were abandoned. While test excava­tions at the base of the carte were conducted in 1979 by Marshall Becker and 1988 by Saul Murillo, no further work was done, even as plans were being made to com­pletely fill in the old river course and consolidate the exposed face of the cortex.

Meanwhile, in the years following the end of the Penn project at Quiriguá in 1979, Sharer and David Sedat (a University Museum Re­search Specialist) began developing another major archaeological project in the Maya area. When those plans became stalled, William Fash, who has been conducting research at Copan longer than anyone (continu­ously since 1978), proposed that Sharer and Sedate consider launching an interim program at Copan. The aim would be to salvage the work begun by Guillemin and to recover as much data about the Acropolis architectural sequence as possible before the carte was finally consoli­dated and sealed.

After studying this proposal, and estimating that the Copan carte work could be realized during the two- or three-year delay expected before beginning work in Guate­mala, Sharer agreed to accept Fash’s offer. Julia Miller was the first mem­ ber of the Penn team to begin work, conducting a feasibility study in 1988 on the remains of Structure 21 (dis­cussed further below). In January 1989 the new Penn program began the first full-scale season of cortex research, and it is now clear that it will take far longer than our original estimate to complete the excava­tions.

The Penn program is part of the Proyecto Arqueologico Acropolis Copan (PAAC), a consortium of programs and institutions that are dedicated to an interdisciplinary investigation of Copán’s Classic period development. As such, the PAAC is one of the heirs to Gordon Willey’s original research plan for Copan. The PAAC is under the over­all directorship of William Fash, with each of the directors of the participating programs serving as co-directors. As of this writing the other consortium directors are Ricardo Agurcia of the Foundation for Pre-Columbian Studies at Copan; E. Wyllys Andrews of Tulane Univer­sity; Rudy Larios, Director of the Copan consolidation program; and Robert Sharer, director of the Penn research, known formally as the Early Copan Acropolis Program (ECAP).

ECAP is charged specifically with investigating the origins and develop­ment of the Acropolis in all stages prior to its final phase and revealing the full sequence of buried archi­tecture. While such evidence exists at most Maya sites, access to the full sequence is usually hindered by the dismantling of later construction to expose earlier buildings. But the torte removes these problems at Copan: all levels of the Acropolis are both visible and accessible for inves­tigation (see Fig. 1). By tunneling laterally from the carte, architecture at any level can be followed and exposed—and evidence of associ­ated activities can be recorded—without destroying later superim­posed construction (see box on tunneling).

After three full seasons of excava­tion (1989-91), over one kilometer of tunnels have been opened to follow the buried structures under the Acro­polis (Fig. 6). These now total 28 platforms and 18 buildings, repre­senting a 400-year sequence of con­struction. Dating of construction levels is based on stratigraphy, sup­plemented by radiocarbon assess­ments, associations with ceramics and other artifacts, and newly dis­covered inscriptions with Maya calendrical dates. Our tunnels also connect to excavations elsewhere in the Acropolis, including the tunnels beneath Structure 2B (with the Hiero­glyphic Stairway) to the northwest, where additional earlier buildings have been revealed that can be tied into our overall sequence.

These excavations have docu­mented the construction sequence of the eastern half of the Acropolis. They also provide independent means for testing the results of recent historical research based on deci­pherments of Copán’s inscriptions. For example, the historical texts refer to a ruler named Yax K’uk’ Mo who apparently founded the royal dynasty about A.D. 42B. Signifi­cantly, the ECAP excavations show that the beginnings of the Acropolis date to about A.D. 400, with the construction of a series of monu­mental platforms and buildings that were placed over an earlier complex of simple, low residential platforms (designated as Division V, ca. A.D. 100-400). These monumental con­structions (Division IV, ca. A.D. 400­500) seem to represent the founding of the first royal administrative, resi­dential, and ritual complex at this locus, to judge by the scale and elaboration of structures, especially their associations with hieroglyphic inscriptions and modeled and painted stucco decorations.

The initial complex was domi­nated by a huge terraced platform, measuring some 50 m north to south, 68 in east to west, and over 9 m in height, that once covered the bulk of the southeast quadrant of the Acro­polis (its original eastward extent is unknown due to destruction by the Rio Copan). In the northeast quad­rant, a lower platform supported a large administrative/residential com­plex of multi-roomed, unvaulted masonry buildings (Fig. 8). Excava­tion thus far has defined eight of these structures, arranged around three courts (Court B, the only adequately defined example, mea­sures ca. 25 m by 20 m). The ex­teriors of these northern buildings were decorated with elaborately modeled and painted stucco reliefs, and at least one interior had a painted hieroglyphic text.

Our research, controlled by the well-defined architectural stratig­raphy of the cortex and recorded by the COMPASS system (see box), allows important insights into the timing and scale of activities spon­sored by members of Copán’s ruling dynasty. Events in Copán’s historical record, such as the ebb and flow of the political fortunes of its rulers, can be compared to shifts or changes in the constructional record under the Acropolis East Court.

We can thus investigate associa­tions between historically identified rulers and specific buildings. For example, a major building platform discovered in 1989 (“Ante”) has been dated to Division II (ca. A.D. 700­800) and hypothesized to have been associated with the 11th Copan ruler, Butz’ Chan, based on its stratigraphic position and iconography (Fig. 9). This hypothesis was further sup­ported by the discovery in 1990 of a reused carved hieroglyphic step on the staircase of this platform. That this particular building was also especially important and venerated by the Maya is indicated by the unusually large inventory of cached deposits of carved jade and other materials we have found along its central axis (Fig. 10).

In the northwest quadrant of the East Court we are excavating the complex architectural sequence un­derlying Structure 22, the largest extant building in this area. We are also tracing the architectural de­velopment of the northeast quad­rant. The Structure 21 research has essentially completed the work be­gun nearly a century ago (1891-92) when the south and west sides were cleared during the Peabody excava­tions. Far less remains today, the entire superstructure and all but the western portion of the terraced plat­form having fallen into the Rio Copan. By exposing what remains and recovering all surviving mosaic sculpture before consolidation and preservation, we sought to identify Structure 21’s function and place in the overall Acropolis sequence. The most reasonable hypothesis based on sculptural motifs and dating evi­dence is that Structure 21 was a mortuary shrine for Copan’s 13th ruler, 18 Rabbit, built between A.D. 715 and 771 by one of his immediate successors, either the 14th or 15th ruler.

Although this identification cannot be considered conclusive, the evi­dence recovered from the investiga­tion of Structure 21 shows how much can be learned by combining ar­chaeological, epigraphic, and icono­graphic data even when the original building has been almost completely destroyed.

Conclusion

By excavating a series of tunnels from the stratified architectural re­mains visible in the corte, the Early Copan Acropolis Program is docu­menting a 400-year sequence of monumental architecture directly associated with Copan’s historically known ruling dynasty. As a result, our research is providing a study of change in architectural form, func­tion, and organization as it relates to the entire life-span of an identified lowland Maya ruling dynasty. Our research is also documenting the architectural layout of a major low­land Maya polity center with all its functional variation. When our work is completed, we will be able to show the Copan Acropolis at each stage of its development to a degree of detail impossible to achieve at other sites. Given the practical and ethical concerns of using destructive conventional excavation techniques to provide such documentation, it seems likely that our investigation of the architectural evolution of the Copan Acropolis will not be dupli­cated any time in the near future.

Over the years, the foundations that Gordon Willey established for the comprehensive archaeological investigation of Copan are being realized. Although his settlement program ended in 1976, other projects have continued to gather environmental, architectural, icono­graphic, and epigraphic data from Copan. As a result, it is the most thoroughly investigated and best known of all Maya sites. This is not to say the work is even close to completion, for so much remains to be investigated, analyzed, and pub­lished that it seems likely Copan will remain a focus of an international research effort for years to come.