That was when the small Spanish army of conquistador Hernan Cortes and thousands of indigenous allies finally captured the Aztec capital of Tenochtitlan -- dooming its rulers and their civilization.
Even some of the Spanish troops realized, after the fact, that they had destroyed something strange and beautiful. One of the last of them, the tough and unsentimental Bernal Diaz del Castillo, looked back many years later when he was an old, blind man in Guatemala and remembered his first sight of the city in Lake Texcoco.
"It was all so wonderful that I do not know how to describe this first glimpse of things never heard of, seen or dreamed before," Diaz wrote. He went on to lament that so much of it was already lost.
The Spanish began the destruction of Tenochtitlan within months of the conquest, and its site is now buried deep beneath Mexico City.
But recent years have brought new excavations in the metropolis of 23 million, and some long-buried Aztec art have been uncovered.
Several of the most striking works from one of those digs, the "House of the Eagles" site, form the centerpiece of the Field exhibition, "The Aztec World: A Unique View of a Mighty Empire."
The exhibition, which opened Sunday, features nearly 300 artifacts, many never before seen outside Mexico. Co-curator Gary Feinman said the works come from 10 major Mexican museums, as well as from the Field's own collection, and the exhibition took four years to assemble.
"That's quite a long time when you consider that the Aztec empire itself lasted only about 100 years," Feinman said.
He said the House of the Eagles appears to have been a building closely associated with the coronation of Aztec emperors, as well as their funerary rites. Two massive ceramic sculptures in the exhibition display both aspects of the site. One is of a mighty winged warrior, while the other is a ghastly image of Mictlantecuhtli, a god of death and the underworld.
Feinman said the winged figure may have been a "spirit warrior," the ascended soul of a soldier who fell in battle. Spirit warriors, he said, accompanied the sun god, Tonatiuh, on his triumphant rise into the sky each morning.
"The spirit warriors flew up with him until the zenith, and then the spirits of women who died in childbirth accompanied him on his way down to sunset," he said.
Sunset would have brought him into the realm of Mictlantecuhtli, who is depicted as a naked figure with a grinning skeleton head and his liver hanging out of his abdomen. In Aztec times, his statue would have been bathed from time to time with human blood.
The exhibition is not a chamber of horrors, though. Many of the displays show the quiet everyday side of Aztec life; its trades and crafts and agriculture.
Some of the smaller works -- particularly those in gold, greenstone, and obsidian -- have a serene beauty missing in some of the larger statues.
And there's even some whimsy in the artifacts.
Feinman pointed to one of his favorite pieces, a ceramic container for pulque, the fermented agave sap that was the Aztecs' favorite intoxicant. The container is in the form of a jackrabbit lying limply on his side with an oblivious expression on his face.
"The rabbit was an Aztec symbol of drunkenness," Feinman said.
"The Aztec World" runs through April 19, 2009. It is not scheduled to appear in any other museums.