Wilson in his _Prehistoric Man_ (i. 246) says: “By the unaided results of native science, the dwellers on the Mexican plateau had effected an adjustment of civil to solar time so nearly correct that when the Spaniards landed on their coast, their own reckoning, according to the unreformed Julian calendar, was really eleven days in error, compared with that of the barbarian nation whose civilization they so speedily effaced.” See what Wilson (_Prehistoric Man_, i. 333) says of the native veneration for this calendar stone, when it was exhumed. Mrs. Nuttall (_Proc. Am. Asso. Adv. Sci._, Aug., 1886) claims to be able to show that this monolith is really a stone which stood in the Mexican market-place, and was used in regulating the stated market-days.] We have reference to a Cholula mound in some of the earliest writers. Bernal Diaz counted the steps on its side.[1009] Motolinía saw it within ten years of the Conquest, when it was overgrown and much ruined. Sahagún says it was built for defensive purposes. Rojas, in his _Relacion de Cholula_, 1581, calls it a fortress, and says the Spaniards levelled its convex top to plant there a cross, where later, in 1594, they built a chapel. Torquemada, following Motolinía and the later Mendieta, says it was never finished, and was decayed in his time, though he traced the different levels. Its interest as a relic thus dates almost from the beginnings of the modern history of the region. Boturini mentions its four terraces. Clavigero, in 1744, rode up its sides on horseback, impelled by curiosity, and found it hard work even then to look upon it as other than a natural hill.[1010] The earliest of the critical accounts of it, however, is Humboldt’s, made from examinations in 1803, when much more than now of its original construction was observable, and his account is the one from which most travellers have drawn,—the result of close scrutiny in his text and of considerable license in his plate, in which he aimed at something like a restoration.[1011] The latest critical examination is in Bandelier’s “Studies about Cholula and its vicinity,” making part iii. of his _Archæological Tour in Mexico in 1881_.[1012]