Calakmul is a massive site, covering about 70 square kilometres of jungle. From about 600 B.C. to 900 A.D., Mayans carved out aqueducts, reservoirs, dwellings and a central city that once served as a home to 50,000 people and rivalled Guatemala’s Tikal as a regional power. Archeologists have only uncovered a handful of Calakmul’s 6,750 structures, as the site was only rediscovered in the late 1920s and excavations began in earnest a mere two decades ago. Guidebooks credit the rediscovery to the American botanist Cyrus Lundell, but residents of the town of Cornhuas, near the entrance to the road to Calakmul, say the honour belongs to Mexican chicleros who ventured into the rainforest in search of sapodilla trees to tap for chicle, the resin used for chewing gum. Today, this area remains much wilder then it was millennia ago. Calakmul’s population peaked between 250 and 700 A.D., during what’s known as the Classic period of Mayan civilization. Like many other Mayan cities, it was slowly abandoned over the next few centuries due to what’s believed to be the combined effects of climate change and too many people eking out an existence in a rainforest ecosystem that could not sustain farming, hunting, irrigation and urban development on a scale that dwarfed what was occurring in the cities of Europe at the time. The Mayan population of the southern Yucatan dwindled further after the Spanish arrived in the New World, bringing diseases that wiped out as much as 90 per cent of indigenous people, who had no immunity to European pathogens. Conflict between the conquistadors, their criollo descendents, mestizos and modern Mayans over the next few centuries ensured the interior of the jungle remained all but unknown. After Lundell visited in 1931, he took notice of the two largest pyramids poking above the forest canopy and dubbed the site Calakmul, using the Mayan words for “two nearby mounds.” It’s unknown what Mayans called the place, though scholars have a good idea about which kings ruled the city during its heyday, thanks to an unusually elaborate series of stelae, which are upright slabs of rock inscribed with Mayan glyphs and calendar dates. Walking around the site, the stelae are impressive if incomprehensible without the services of a guide. But you don’t need assistance to appreciate the scale of the city or views of the seemingly endless jungle from the top of Calakmul’s pyramids. The panorama from the summit of the 45-metre Structure II, which faces Calakmul’s main plaza as well as low rolling hills in the distance, is outstanding. Structure I, nearly as high, affords an unobstructed view well into Guatemala; On a clear day, it’s reputedly possible to see the pyramids of El Mirador, more than 40 kilometres away. Archeologists have also excavated tombs at Calakmul containing masks made out of jade, but the priceless objects have been carted away to a museum in the city of Campeche for safekeeping. An elaborate wall mural depicting rare scenes of ordinary village life, unearthed only 12 years ago, remains off limits while the site’s administrators determine how to both protect the scene and display it to the public. The ancient city is not the only reason to visit Calakmul. The relatively pristine state of the jungle surrounding it, protected by the Calakmul Biosphere Reserve, means the wildlife-watching opportunities are excellent, especially if you arrive early in the morning. Driving before dawn along the 60-kilometre road to Calakmul from Mexico’s Highway 186, you must travel slowly to avoid crested, pheasant-like birds called great curacaos and colourful ocellated turkeys, the latter of which have a questionable habit of trying to run alongside and in front of vehicles. White-collared peccaries, which are relatives of pigs, and the rotund rodents known as agoutis bounded along the road. I was also lucky enough to see a pair of tayras — odd-looking members of the weasel family, with white heads, black bodies and long, bushy tails — dart across in the distance. At Calakmul, troupes of spider monkeys swung across the forest canopy while more curacaos strutted about below. I spotted two types of colourful trogons in the trees but failed to see any of the toucans who taunted me all day with their frog-like croaks. This was frustrating, because these large-beaked birds, dubbed “flying garden shears” by travel writer Ronald Wright, aren’t exactly inconspicuous. Outside of the Calakmul site, it’s impossible not to see the flying creatures that emerge every evening full at El Volcán de Murcielagos, (the Volcano of Bats,) a cave located 12 kilometres east of the Calakmul entrance-road gate. An estimated 3.5 million bats, belonging to nine different species, spend their days inside this cave, which is an ancient, dry cenote — a hollow cavity in the porous limestone. At dusk, the winged mammals emerge from the cave in a vortex that whips up a warm, guanoscented wind that’s strong enough to cause trees to shake. The bats swirl about for nearly half an hour, darkening the skies before they stream out into the jungle in search of insect prey. This spectacle alone makes Calakmul a worthy visit for a nature nerd. The abundance of wildlife, the ancient city and the chance to enjoy it in the presence of very few other people make it a compulsory stop for anyone who has the time to get away from the Caribbean-sea tourist drags and explore a bit more of the Yucatan Peninsula.