Hieroglyphic Stairway at Copán

The archaeological site of Copán is located in western Honduras, near the border with Guatemala. During the Maya Classic Period (250 CE–900 CE), Copán was one of the dominating polities in the region, as evidenced by its monumental ruins.

Since its rediscovery in the late 19th century, the site has been extensively investigated and excavated, revealing elaborate architecture and sculptural monuments. Covering approximately twelve hectares, the central area of the site is made up of a series of large buildings organized around open plazas. Copán is perhaps best known for its stone carving, including its stelae, altars, and spectacular Hieroglyphic Stairway. At ten meters wide by twenty-four meters high, the stairway is the longest text carved on stone from ancient Mesoamerica—comprising sixty-three steps with over one thousand intricately carved glyphs. This unique text recounts four centuries of Copán dynastic history.

When the stairway was rediscovered and excavated, only the lower fifteen steps were found in their original position. The remaining steps were reconstructed during 1937 to 1940 using original fallen blocks that archaeologists had collected on the plaza in front of the pyramid structure. Beginning in the 1970s, concerns for the preservation of the stairway prompted measures to protect and conserve it. The public was no longer allowed to walk on it, and a variety of conservation treatments were carried out on the stone surfaces. A canvas shelter was first installed over the stairway in 1985 and has been periodically replaced as needed.

The deterioration of the hieroglyphs on the stairway risers has been a major cause of concern to scholars, conservation specialists, and IHAH because it directly impacts the ability to read the carved stone text.

Between 1999 and 2005, a team of conservators and scientists from the Conservation Institute working with IHAH undertook a series of studies and analyses to better understand the conditions and behavior of the materials. This collaborative and interdisciplinary project included three major areas of study conducted by the team:

• Archival research was carried out to locate written and photographic documentation, and detailed surface conditions of each block were recorded digitally in order to evaluate past and current stone conditions of the stairway.
• Biological specimens taken from the stone surfaces were identified, and stone and mortar samples from the site were analyzed in the laboratory to define their characteristics and to assist in identifying causes of deterioration of the constituent materials of the stairway.
• Environmental monitoring equipment was installed to determine how current stone surface conditions were related to present climate data for the site and to record environmental conditions such as temperature and moisture on the surface of and below the stairway blocks.

To support the mapping of the conditions of the stairway stone blocks, a full photographic record was undertaken. Stereo photography (photogrammetry) was used to provide further comparison of the condition of the stone and to provide data for an eventual three-dimensional model.

Conservation treatment trials, both for stone surface stabilization and mortar repointing, were carried out on selected blocks of the stairway to determine which stabilization methods were most effective, appropriate, and sustainable for future applications.

Another aspect of the Copán project was to define parameters for a protective shelter in order to develop guidelines for appropriate sheltering measures. Today there are several types of shelters at the site to provide protection for carved stelae, decorated buildings, and the Hieroglyphic Stairway itself. While visitors are especially sensitive to the aesthetic impact of these added shelters, it is important to understand what beneficial effects they have in relation to their shape, form, and materials.

The conservation plan for the stairway is substantiated by a comprehensive condition assessment and evaluation of treatment trials. It considers the need for the stabilization of the stone blocks, surface repair/replacement of mortar and parameters for a new shelter design. It also includes preventive measures, short- and long-term maintenance actions as well as a monitoring program to evaluate the condition of the stairway over time. To implement some of these measures, selected employees of IHAH and other project members at Copán were trained in photographic monitoring.

Work Completed

• close-range stereo photography
• characterization of stone materials, mortar and decay products, as well as of repair materials used on the Stairway
• detailed condition reports of the stone blocks, recorded in digital format
• identification and evaluation of effects from the biological colonization of stone surfaces
• design and installation of on-site environmental monitoring system
• extensive archival research and annotated bibliography
• comparative analysis of photographs of selected blocks taken over time
• characterization of the environment at the site and of microenvironment under the shelters
• research on locally available and potential treatment materials
• results from treatment trials for repointing with lime mortars and of stone surface treatments
• schematic drawing of entire Stairway with numbering system

A final project report, The Hieroglyphic Stairway of Copán, Honduras: Study Results and Conservation Proposals, available in English and Spanish, synthesizes all the studies and establishes proposals for the stabilization of the carved surfaces as well as preventive measures and maintenance.

It was officially presented in July 2007 at four events that took place, respectively, in Tegucigalpa, the capital of Honduras, in the presence of the Minister of Culture; the city of San Pedro Sula; and the town of Copán, first with professionals involved at the site and then to the larger local audience.