Travel: Mexico - High plains drifter

If the chocolate moles don't tempt you, then the Mariachis surely will. Polli Kaminski escapes to the ancient, unspoilt gem of Oaxaca

"Well" said my friend, who had lived for some time in Africa, "I have eaten hippopotamus, so why not mole?" We were skimming the menu in a Mexican restaurant. Mole in Mexico ("molay") is not, she was relieved to learn, a small black creature that digs up mounds in the lawn, but a delicacy that originates in the city of Oaxaca (pronounced "Wahaka") in the heart of Mexico.

Streets around the main market here are crammed with mole shops, each selling its own style of this chocolaty, herby, spicy sauce, which is cooked up and served with chicken, turkey, beef or anything else you fancy. My favourite was a really rich plate of fried potatoes immersed in it. Once you have got over the thrill of eating really fresh tacos and mountains of guacamole with refried beans, it becomes clear that the cuisine of Mexico, while interesting in the composition of some dishes (huevos rancheros, for instance - fried eggs on a bed of spicy green salsa), is not blessed with infinite variety. Mole, which gives Mexican food that small note of individuality, can also contribute to a person's status, as can be seen in the recipes specially made up for important Oaxacan families.

Apart from this unusual little delicacy, Oaxaca can boast of being possibly the most beautiful city in Mexico. High on the plains in the heart of Oaxaca state, 300 miles south-east of Mexico City, it shines with a light similar to that in Mediterranean cities. Combine this with the air purity peculiar to high altitude and minimal industry, and the effect is stupefying.

Oaxaca is built on a grid system similar to that of New York, but is a fraction of the size; at the end of every long, straight street the city disappears and fresh green hills rise up, leaving you with a disconcerting sense of being cut off from the world.

When the Spanish moved inland from the coast in 1520, they brought with them architecture typical of southern Europe, which can still be seen in the heart of the city. Large, noble buildings are painted in earthy colours - sand red, ochre and stone - and adorned with wrought-iron balconies crammed with pots of trailing flowers. Through huge wooden doors, high courtyards are massed with tumbling and creeping greenery. Regal stone staircases lead up to cool and shady rooms where quiet voices echo intriguingly.

All streets eventually lead to the zocalo, or main square, the heart of every city in Mexico. But Oaxaca's is different. It is bordered on one side by a flowery, Rococo-style church and on all other sides is crowded with cafe and restaurants, their chairs and tables laid out invitingly in the sun or tucked shyly away in the shade of arched walkways.

In lush gardens at the heart of the square looms the bandstand, a stage for the talents of earnest young people and practised adults who proudly play on Sunday afternoons and saints' days. Everyone congregates in the zocalo: children play, plots are laid, and business deals are negotiated in the shade of the trees.

On the borders, beggars and street urchins do their rounds of the restaurants and cafes, ostensibly selling bits of carved wood or ribbons. The best thing to do is to let them eat your tacos and salsa, and give them bread and butter from your table. Even the poorest give to the poor in Oaxaca. And poverty is here in plenty.

When darkness falls, the music starts up and every cafe on the zocalo bursts into sound, each one offering a different style. Young people with extraordinary talent play guitars, pipes, accordions. Others sing. Whatever their chosen skill, their presence is magical, and the square becomes sadly empty when they finish for the night - usually around midnight.

When wailing and strumming starts up around the square, you know the Mariachis have arrived - groups of local players and singers, romantic buskers who invariably play quite badly and sing slightly out of tune, but have masses of charm. And, oh, those trousers ... Low at the hip, flared at the foot, with silver studs from waist to ankle down each side and silver-studded belts, they are uniform to the Mariachis but coveted by just about every female tourist in Mexico.

Close by the zocalo is the other centre of Oaxaca, the covered market - a place of loud voices and bright colours. Everything can be bought here, from dustbins to leather handbags, and there is a stall selling fruit and vegetable juices where you can realise your barmiest recipes: coconut and mango, carrot and guava, and more.

It would be reckless to visit Oaxaca and to miss the magnificent site of Monte Alban. Set on a hilltop about six miles from the city, it is one of the most important pre-Hispanic ruins in Mexico. It was once the Zapotec capital, and archaeologists have dated its origins to 500BC. Most of the ruins existing today, however, date from AD300-750. The technology required to design and build such a huge complex, which housed a highly organised society, is staggering.

Many treasures were plundered over the centuries, but in 1932 Dr Alfonso Caso discovered Mixtec treasures that had been buried in tombs. Some of these can be seen in the modern museum at the entrance to the site. Meanwhile, if you feel like experiencing life as a true Mexican mole you can visit the vaulted burial chamber, Tumba 104.