System IV at Monte Albán: Research Synthesis

This institutional research report examines System IV, or Sistema IV, a monumental ceremonial complex located at the northwest perimeter of the Main Plaza at Monte Albán, Oaxaca. The complex represents a highly developed example of the Zapotec Temple-Patio-Altar arrangement, integrating a frontal platform, enclosed sunken courtyard, central altar, rear temple platform, subterranean circulation, drainage infrastructure, and the adjacent Stela 18. The report analyzes how System IV controlled movement and visibility through blind entrances, narrow corridors, enclosed ritual space, and underground tunnels. These architectural features restricted access to elite ceremonies and allowed high-status participants to move discreetly between platforms, creating staged appearances and disappearances during public ritual. Particular attention is given to Stela 18, a monolithic column approximately 5.8 meters high that may have functioned as a gnomon for observing midday, solstices, and the twice-yearly zenith passage of the sun. Its calendrical and genealogical associations connected the regulation of sacred time with the political legitimacy of Zapotec ruling families. The report also examines System IV’s architectural symmetry with System M, its relationship to earlier buried structures detected through geophysical research, its hydrological engineering, and the high-resolution three-dimensional documentation produced by CyArk and Open Heritage 3D for structural monitoring and conservation. This Zenodo record preserves Version 3.0 of the research report together with a supporting photographic archive. Document ID: MA-STR-IV-2026. DOI: 10.5281/zenodo.21635046.