Monte Albán — Stela 18

Stela 18 is the oldest and tallest carved stone monument at Monte Albán, serving as an astronomical instrument for verifying midday and solstices, with inscriptions possibly related to a calendar.

Stela 18, also known as Estela 18, is a carved stone monument located outside the north wall of System IV in the northwest corner of Monte Albán’s Main Plaza, dating to approximately 100 BCE–300 CE. As the oldest and tallest stela at this Zapotec ceremonial center in Oaxaca, Mexico, it features glyphs and incisions believed to relate to calendrical functions, serving as an astronomical instrument to verify midday—one of the four Pre-Hispanic divisions of the day—and mark solstices and equinoxes. Its significance lies in highlighting Zapotec astronomical knowledge and ritual practices, integrated into the site’s sacred topography as a boundary marker. [1] [3]

Location and layout

Stela 18 stands outside the north wall of System IV, positioned in the northwest corner of Monte Albán’s Main Plaza, which measures approximately 300 m (984 ft) by 200 m (656 ft). This location serves as a corner boundary to the site, part of the western row of symmetrical complexes including System M and Building L. The stela is vertically oriented, facing east-west, with its placement facilitating astronomical observations visible from the plaza, relating to nearby features like the North Platform and emphasizing its role in the site’s processional and ritual layout. [1] [4]

Architecture and construction

Carved during Monte Albán II (100 BCE–300 CE), Stela 18 was constructed from local stone, standing 5.8 m (19 ft) tall, with surfaces incised using pecking techniques typical of Zapotec monument production. The stela features a rectangular form with carvings on both sides, oriented for solar alignments. Construction aligns with the site’s Classic period, positioned to interact with sunlight for timekeeping, without later modifications noted. [1] [3]

Sculpture and epigraphy

Stela 18 is distinguished by its incisions: the eastern side bears two glyphs, including a water sign, while the western side has carvings possibly related to a calendar, reflecting Zapotec iconography tied to astronomical and ritual themes. As the oldest monument at the site, its epigraphy may indicate calendrical notations, serving propagandistic or commemorative purposes, though interpretations remain tentative due to the early nature of Zapotec script. [1] [5]

Archaeological research

Documented during Alfonso Caso’s 1931–1953 Monte Albán Project, Stela 18 was excavated and analyzed for its stratigraphic context, dated via associated ceramics. Anthony Aveni’s studies identified its astronomical function, confirming alignments for midday verification and solstices through observational data. Modern research employs 3D scanning for preservation, with debates on glyph interpretations but consensus on its timekeeping role. [3] [6]

Visiting notes

Visitors can view Stela 18 from the northwest corner of the Main Plaza near System IV, appreciating its height and position for solar observations, following a counterclockwise interpretive path that contextualizes its astronomical significance. [4]

Related MAHC WIKI entries

System IV
Main Plaza
Building J
North Platform

References

Sullivan, Mary Ann. (n.d.). “Monte Albán: System4/Edifice K and Stele 18.” Bluffton University. https://homepages.bluffton.edu/~sullivanm/mexico/oaxaca/montealban/system4.html. Description and images of Stela 18.
UNESCO World Heritage Centre. (1987). “Historic Centre of Oaxaca and Archaeological Site of Monte Albán.” https://whc.unesco.org/en/list/415/. Official listing.
Mexico: Monte Alban. The Silk Route. http://www.the-silk-route.co.uk/mexicoMonteAlban.htm. Details on height and age.
Planeta.com. “Monte Albán.” https://www.planeta.com/monte-alban/. Astronomical function.
Travel with me. “The magic of Monte Albán.” https://www.toonsarah-travels.blog/the-magic-of-monte-alban/. Height and astronomical use.
Monkey’s Tale. “The Pyramids of Monte Albán.” https://monkeystale.ca/2024/09/03/the-pyramids-of-monte-alban/. Confirmation of astronomical instrument.