Lustrous Silver City eludes the tarnish of Mexican tourism

It was on a random street in Guanajuato that I first felt I had really arrived in Mexico. I was walking alone, hands shoved in my pockets, through the narrow, crowded lanes of this bustling little Mexican city, when I suddenly realized two things. First, it had been a couple of days since I had seen another person from the United States. Second, I was lost.

Both came as welcome revelations, because I had heretofore been all too frequently reminded of the states and all too located on a well-marked path.

Not that the path and the connections had been totally without charm. You'd have to go a long way to improve on the charms of San Miguel de Allende, a few hours' drive from here, or the historic-architectural attractiveness of Queretaro, another half-day's journey along the Silver City arc in this rugged corner of the central Mexican plain. Both towns absorb you in that peculiar Mexican mixture of languor and struggle that haunts this country's landscapes and small plazas.

Still, there had always been - from the time I landed in Mexico City's airport on a warm January afternoon, browsed the city's museums and shops, and finally traveled the main artery heading north through the Silver Cities - the unshakable feeling of being a disengaged observer. In short, I felt like a tourist.

For me, the moment of becoming ''un-disengaged,'' and something other than a tourist, came in Guanajuato.

Capital of the state bearing its name, Guanajuato is also the most intellectually intense, commercially active, and wealthy of the Silver Cities. This nickname refers to the historical role of these cities during the 17th and 18th centuries, in providing Spain and most of Europe with enough silver to keep continental craftsmen's fingers unendingly engaged. Today the region still produces much metal ore, including silver, but the tourist will find little in the way of old mines and silver crafts to give evidence of this fact.

Guanajuato is best known, among tourists, for its ornately varied architecture, for the Panoramica - the mountain road that runs along a horseshoe ridge high above the city - and for its grisly ''mummies'' - actually corpses buried for a minimum five years, unearthed for new burials, and gruesomely preserved by an accidental combination of minerals in the local soil.

The city's intellectual life, however, thrives on the university and the cultural elite it attracts. In Guanajuato, you feel the bruit of ideas and opinions.

The night I got lost there, I was drifting through teeming streets after wandering around the Hidalgo, a polyglot, indoor market in a building that looks like a massive, antique European railway station. My walk took me past narrow, faceless stores selling television sets at prices the average Mexican couldn't even dream about, and shuttered shops that deal in cloth, hardware, and the goods of everyday life. Everywhere I had to elbow my way through small knots of pedestrians or step out onto the street to miss them.

In a way, the experience was reminiscent of nighttime Queretaro, the aged town about 80 miles southwest of Guanajuato, which at night has all the tranquil walkability of a modern race track. There, one had to plow through crowds as well. But Queretaro's crowds seemed mostly to be bored tourists on a desultory holiday.

Perhaps that's because it only takes two or three hours' driving from the capital, at the average posted 100 kilometers per hour (about 62 m.p.h.), to come into that most historic and frequently visited of the Silver Cities. There, you and a few thousand other tourists, Mexican, US, and other nationalities, walk through the traffic-choked streets at night or shamble in the hot sun from site to site, as church bells toll the hour.

This shambling takes you to some crucibles of the Mexican war of independence and other historical finds. Queretaro shines best in sunlight, when you can peek into colonial courtyards or wander into cave-dark churches and oddity-crammed shops. Off the main roads, strings of flagstone byways twist between high walls and intimate squares.

In such sun-drenched surroundings, you get the feeling that the only intelligent thing to do is to sit under a spreading tree and let the afternoon pass quietly into eternity. It seems almost too much work to get to the outskirts of town and the famed los arcos, the arched aqueducts.

Guanajuato is quite different. Guanajuato is real life. Almost everybody there is in the city for a reason connected to his livelihood. Students and artisans and artists and shopkeepers - they all seem to have a vital link to the city's life. And yet the spectacle of Guanajuato - its weathered physique and mysterious evocations of the past, as well as its high energy - draws them all out at night, too, looking at one another, prowling the streets, getting into heated arguments, playing cards.

Both before and after the night I got lost there, I saw more of Guanajuato. But I never saw it better.

The next day, I looked at a prettier view of Guanajuato from the Panoramica. A drive across the Panoramica is a journey through the topography, and the poverty, of the state. Worked into the folds of the mountain basin-side, the road passes giant rock formations, children on tricycles with broken wheels, braying donkeys, and a whining buzz saw. Through it all, there is the near-distant spectacle of Guanajuato.

The other drive offered by Guanajuato runs under the city itself, through ancient sewers and water tunnels. The city's streets are too narrow and crowded to accommodate much traffic; so everyone drives in the subterraneo, a fast-moving honeycomb of confusing turnoffs and sometimes harrowing goosenecks.

The experience of suddenly coming into the subterraneo, after driving over from San Miguel de Allende, can disorient and even frighten you a bit.

That's because San Miguel remains the quintessential sleepy Mexican village, in spite of the influx of American residents and tourists into this haven for expatriate artists and writers. San Miguel manages to bustle without ever really waking up. It is known as a place to get away from city pressures and competition and ''the terrible speed of life,'' as local writer Robert Somerlott - who came for a weekend 18 years ago and never left - puts it. The village lives up to its reputation.

Residents of San Miguel joke about the time when Lady Bird Johnson made a visit and the Secret Service reportedly called ahead to ask for ''a Hilton-style hotel with air conditioning'' and all the other conveniences.

San Miguel is not air conditioning and conveniences. It is in the continued tradition of good living established by those who first grew wealthy off this region's silver lodes, a couple of centuries ago - all of it placed squarely within the homely poverty of central Mexico. You can choose from the lofty, barrel-vaulted suites of Mexican film star Cantinflas's former hillside residence and the small, elegant hotels down in the village proper. You can eat well and see much art and be charmed by it all. You can admire, and perhaps purchase, the work of local tinsmiths, for which San Miguel is famous.

Somehow, though, I wasn't unhappy to leave San Miguel for Guanajuato. Cantinflas's joke, that he didn't speak enough English to live in San Miguel, bore some underlying truth for me, even if the Mexicans outnumber foreigners by a couple of thousand to one.

Along the road from San Miguel to Guanajuato, the distant Sierra Madre rim the horizon with a dull umbra. Young children lead reluctant bulls down timeless paths. The whole world looks leathery and ancient.

It's an implausible setting for a city like Guanajuato, which just erupts from the sleepy ambiance around it. But Guanajuato is quite vigorously and undeniably there. It acts as a small cultural engine for this provincial region, a chunk of urban mania stuck in the midst of quaint, rustic life.