The area around San Gervasio (Cross-Island Hwy. Km. 7.5, www.cozumelparks.org.mx , 7 a.m.–4 p.m. daily, US$7) was populated as early as A.D. 200 and remained so after the general Maya collapse (A.D. 800–900) and well into the Spanish conquest. In fact, archaeologists excavating the ruins found a crypt containing 50 skeletons along with numerous Spanish beads; the bodies are thought to be those of 16th-century Maya who died from diseases brought by the conquistadors.
Today’s visitors will find a modest ruin, whose small square buildings with short doors are typical of those found elsewhere on the island. This style, known as oratorio, almost certainly developed in response to climatic imperatives: Anything built here needed to withstand the hurricanes that have pummeled Cozumel  for millennia. (Sure enough, Hurricane Wilma did no major damage to San Gervasio’s structures.)
San Gervasio has three building groups that are accessible to the public—Las Manitas, Central Plaza, and Murciélagos; all are connected by trails that follow the same ancient causeways used by the city’s original inhabitants. A fourth building group—El Ramonal—is not yet open to the public.
Entering the site, you’ll come first to the building group named after the structure Las Manitas (Little Hands) for the red handprints still visible on one of its walls. This structure is thought to have been the home of one of San Gervasio’s kings, Ah Huneb Itza, and the inner temple was likely a personal sanctuary. Just east of the Las Manitas building is Chi Chan Nah; consisting of two rooms, it is the smallest structure in San Gervasio. The exact purpose of this building is unknown, though it is theorized that it was used for rituals.
Bearing left, the trail leads to the Central Plaza, a large courtyard surrounded by nine low structures in various states of decay; it is believed that the structures were made taller with wood extensions. The Plaza Central served as the seat of power in San Gervasio’s latest era, from A.D. 1200 onward. At the northwest side of the Plaza Central is the somewhat precarious-looking El Arco (The Arch), which served as an entrance to this section of the city.
At 0.5 kilometer (0.3 mile) from the Plaza Central is the Murciélagos (Bats) building group, containing the site’s largest and most important structure: Ka’na Nah (Tall House). Also dating to San Gervasio’s later era, this was the temple of the goddess Ixchel, and in its heyday would have been covered in stucco and painted red, blue, green, and black.
Finally, on the northeastern edge of San Gervasio rests Nohoch Nah (Big House), a boxy but serene temple. With an interior altar, the temple might have been used by religious pilgrims to make an offering upon entering or leaving San Gervasio. It was originally covered in stucco and painted a multitude of colors.
Guides can be hired at the visitors center for a fixed rate: US$20 for a one-hour tour in Spanish, English, French, or German. Prices are per group, which can include up to four people. Tips are customary and are not included in the price.