The earliest traces at La Campana date to roughly 900 BCE, but the broader Colima region shows human settlement reaching back about three thousand years. Vestiges of Capacha phase ceramics dating to 1500 BCE were found on the site. The Capacha Culture, a sedentary people dedicated to agriculture and ceramics production, occupied the area between 2000 and 1000 BCE. A later settlement at nearby Los Ortices, active from 300 BCE to 300 CE, produced finer pottery and stone sculpture and buried its dead in the shaft tombs characteristic of western Mexico. By the early sixteenth century, Purepecha groups dominated the region, but the Tecos -- who controlled the valuable Tzacoalco salt mines -- waged a salt war under their leader Coliman that reshaped the political landscape. The Tecos took Sayula, Zapotlan, and Amula, becoming the predominant group before Spanish contact.

At the heart of the explored zone stands Structure 2, a pyramid altar built on three square stepped platforms with four staggered entrances leading to the top. Its sloped silhouette echoes the profile of the nearby Volcan de Fuego -- the fire volcano -- and archaeologists believe this resemblance was intentional, that the volcano was a central cult object. Structure 1, the largest excavated building, sits on a rectangular base measuring 52 by 36 meters, with overlaid stepped platforms and broad stairs ornamented by stone cubes. Inside its upper temple, circular wells may have stored grain or the ashes of priests and warriors. Human skeletal remains were found on both sides. The stucco that once covered these buildings was fired to hardness and possibly painted with mineral pigments. Traces of vegetable fibers mixed into the adobe suggest construction techniques refined over centuries.

The shaft tombs of La Campana are among the site's most revealing features. Near Structure 6, Tomb No. 7 contained a vaulted burial chamber reached by a stepped corridor. Inside were fragments of human remains alongside offerings both domestic and ceremonial -- including a clay dog and a clay mask, objects intended to accompany the deceased on their journey to the underworld. Multiple burials found during excavation share a curious pattern: skeletons frequently lack hands, feet, and portions of the rib cage. The site's funeral customs point to complex beliefs about death and the afterlife that connected La Campana to broader Mesoamerican traditions. Between Structures 5 and 6, a ballgame court oriented east to west hosted Tlalchi, the ritual ball game associated with fertility and political-religious power. Even after the city declined, people returned here for ceremonies.

The Cascabel Pyramid takes its name from a rattlesnake sculpted in stone at the base of its primary stairway. The serpent is symbolically linked to the water cult -- it represents Tlaloc, the rain god, associated with clouds, lightning, and the cyclical return of the rains that sustained agriculture in this volcanic valley. Tlaloc was conceived as a fire snake that passed through the region and, upon falling, sank into the ground. Similar representations appear in Teotihuacan temples, and site studies confirm connections between La Campana and classical period Teotihuacan culture. The Spaniards who arrived in 1524 found the place still known by its original name, Almoloyan -- "place between two rivers." The current name, La Campana, came later, coined by the site's casual discoverers who thought the mound where they found it resembled a bell. It was listed in the Mexican archaeological heritage register in 1917, but the site did not open to the public until 1995.