'The ancient Maya believed that each time you pass through this doorway you would become a year younger", said Alfredo. Despite having to bend almost double, I tried it three times; it's easy to suspend Western rationalism here in the magical surroundings of Edzna, one of the cities mysteriously abandoned by the Maya around 1,000 years ago.
The centrepiece is the five-storey pyramid, a palace-cum-temple with an array of 40 doors and a unique curved wall down which a waterfall once cascaded. There's a very special kind of beauty in these dramatic, semi-restored grey stone monuments set in broad grassy clearings in the jungle.
In Edzna's little museum is a collection of stelae, the standing stones which recorded and commemorated key Mayan events in hieroglyphs, and sculpted figures with elongated heads and cross-eyes. Such features were considered the peak of physical beauty by the Maya, who took cruel measures to develop them in chosen children.
Campeche state is the hidden, exotic face of Mayan Mexico. Its 400-kilometre coastline stretches down the west side of the Yucatá* peninsula, away from the beaches of the Riviera Maya and the bright lights, night clubs and super-hotels of Cancun, which have long been within easy reach of British travellers. (Virgin Atlantic joined the party this summer, introducing a new route from Gatwick to Cancun.) However, most visitors are still unaware of the tranquil city of Campeche, waiting across the peninsula, and the deserted, historic sites and accessible jungle that lie in the surrounding state.
It took five hours for Alfredo and me to drive – mostly by motorway – from Cancun to his home state. Alfredo is one of the 90,000 people (more than 10 per cent of the population) who still speak the Mayan language in Campeche. He's keen to introduce visitors to the culture of today's rural Maya.
A short drive from Edzna is the village of Ich-Ek, where we met a group of women who have set up a co-operative to save a native, stingless bee, whose habitat is being destroyed by logging and forest burning; they sell honey and beeswax candles. The group's spokesperson is a small, feisty woman in her early sixties, called Leydi. Among the sacks, tools and chickens crammed into the yard outside her home, was a neat pile of logs. On closer inspection, I saw they were pierced with small holes, through which a stream of tiny bees came and went. Leydi told me that the bees were treated like members of the community: "When there's a death in the village, we put a crucifix on the hives," she said, "so they can understand our sadness."
Campeche's capital is the port of San Francisco de Campeche, a neat, relaxed city of 250,000 people – so relaxed, in fact, that the adjective "campechano" is defined in the Mexican dictionary as "laid-back and friendly". Even the sea, beyond the three kilometres of palm-lined esplanade, seemed unnaturally flat and calm. The Old Town has gained Unesco recognition for its colonial Spanish architecture – a mixture of small two-storey houses and much larger mansions, built between the 16th and 19th centuries, now restored and painted in pleasing shades of blue, ochre and ox-blood red.
The pretty central square is the arcaded Zocalo, where the cathedral, a gaunt and austere affair, displays the ravages of the salt-laden sea breeze on its blackened limestone exterior. On the heights above Campeche, the fort of San Miguel, complete with cannons, moat and drawbridge, provides sweeping views over the bay. There's also a fascinating little Mayan museum, whose treasures include tiny, detailed figurines, found at the burial site on the nearby Jaina Island.
Alfredo and I celebrated the day's sightseeing – a bit of an effort in the extreme humidity – with a refreshing, and very welcome margarita. Happily, this could be counted as research, because the word "cocktail" is supposed to have been coined here, when British pirates discovered that local drinks were served with a bird's tail feather as a stirrer.
In comparison with the well-known Yucatá* fleshpots of Cancun and the Riviera Maya, or the developed Mayan sites of Chichen Itza and Uxmal, Campeche has hidden its light under a bushel. A project to change that has just been inaugurated at Aak-Bal, a 30-minute drive south of Campeche city. Set beside one of the white sandy beaches that interrupt the coastal mangroves, are apartment blocks and a beach restaurant, due to be joined over the next couple of years by hotels, a marina and the essential Jack Nicklaus- designed golf course.
For the time being though, Campeche's main attractions require a bit of searching out. This is certainly the case with Calakmul. A four-hour drive from Campeche, almost on the border with Guatemala, this Mayan site brings out everyone's inner Indiana Jones. Here lie the remnants of a city which was once home to more than 50,000 people. Only a small proportion of its buildings have been restored, leaving the stage free for the flora and fauna.
Alfredo pointed out a tree nicknamed "Palo de Gringo", for its papery red bark, which flakes off in the sun's heat; I nervously reapplied my sunscreen. Somewhere in the ocean of greenness were jaguars and harpy eagles. This was the authentic Campeche, ripe for further exploration, and, if you visit Edzna, also promising the secret of eternal youth. In my case, I'm sorry to report, that last element has yet to be delivered.
Mick Webb travelled with Virgin Atlantic (0844 874 7747; virgin-atlantic.com), which flies twice-weekly from Gatwick to Cancun. Alternatively, BA (ba.com) flies from Gatwick, while Thomson Airways (thomson.co.uk) and Thomas Cook (thomascook.com) offer charter flights.
Virgin Holidays (0844 557 3859; virginholidays.co.uk) offers a week’s all-inclusive at the Royal Hideaway, with a seven-day tour of the Yucatán, including Campeche, from £2,889pp, inc flights.
The Hacienda Puerta (starwoodhotels.com). Doubles US$180 (£120).
The Don Gustavo (casadongustavo.com). Doubles from US$180 (£120). Both without breakfast.