"Columnar stela standing 7.3 m [24 feet] above the present surface. This is the first monument dedicated on the northern Plaza Platform, and it appears to have set precedents for the rest of the stelae in this cluster. Monument 6 initiates the practice of twin frontal portraits of Cauac Sky on the southern and northern sides, followed on Monuments 1, 3, 4, and 5 (although the northern portraits on Monuments 1 and 3 are variants in this pattern). The twin portraits on Monument 6 are very similar, but not duplicates."
Robert J. Sharer, Quirigua: A Classic Maya Center & Its Sculptures, Carolina Academic Press, 1990, p. 39