Reporting from Los Angeles and Mexico City — Ever since the Fab Four started playing the Cavern Club in Liverpool, certain rock acts have been linked inextricably with certain cities. It practically defies imagination to picture Lou Reed honing his downtown Manhattan hipster-poet's chops in, say, Yazoo City, Miss.or Kurt Cobain and Nirvana slouching toward grunge-dom while drenched in the sunshine of South Florida, rather than soaking in Seattle's melancholy drizzle.

For the last 20 years, the definitive Mexico City band Café Tacuba has set a series of high-water marks for progressive Spanish-language rock, collecting critical hosannas along with Grammy awards and other trophies by the truckload.

Constantly innovating while relentlessly assimilating new influences from hip-hop to traditional Mexican regional folk and indigenous music, the quartet -- vocalist-guitarist Rubén Albarrán Ortega, keyboardist and guitar player Emmanuel "Meme" del Real Díaz, guitarist José Alfredo "Joselo" Rangel Arroyo and bass player Enrique "Quique" Rangel Arroyo -- has shed its musical skin and sprouted new ones as routinely as an iguana.

It subtly has refashioned its identity almost as frequently as the diminutive, peripatetic frontman Albarrán has changed stage names (he currently goes by the moniker Ixaya Mazatzin Tleyotl).

With L.A.-Argentine mega-producer Gustavo Santaolalla, the George Martin of Latin rock, shepherding its studio releases, the Mexican quartet has even been awarded the ultimate sobriquet by one critic who dubbed them the Beatles of rocken español.

Yet throughout its evolving two-decade career, at least one constant has remained: the band's close identification with its Mexico City home and the (occasionally manic) energy and myriad influences that it absorbs from that sprawling, gritty, baroque megalopolis of 22 million.

"The city's a very large theme for our music," Quique said in English in a backstage interview with his bandmate Meme before a concert last Saturday at Mexico City's vast Foro Sol. "A lot of the things we have lived in this city is what we talk about. And I think after all these years we still speak as people from a neighborhood on the suburbs of Mexico City, living with these people."

Even now, Meme said, he feels excited but "very nervous" whenever he plays before the hometown crowd.

"There are many feelings involved with our families, friends, closest friends since we start 20 years ago," he said. "There are going to be tonight everybody, and there's something that it can't be reproduced in any other city."

Considering the slangy colloquialisms that pepper its lyrics, its distinctly concrete-jungle fashion attire, the fierce, proprietary loyalty it inspires among legions of followers in the nation's capital -- an intense partisanship reminiscent of a tribe of fútbol fans -- Café Tacuba is unequivocally a Mexico City band, albeit now one with a global following.

The group brought its urban chilango sensibility to the Foro Sol, which was packed with 55,000 delirious, screaming fans. At one point in the nearly four-hour show, Albarrán paused from leaping around the stage, his longhair whipping around his shoulders, to ask the crowd how they planned to get home because the Mexico City public transport system shuts down late at night. "Ring your mom and tell her to come get you," he joked.

Presumably, they'll bring the same mix of informality and genial irreverence to Universal City's Gibson Amphitheatre on Wednesday, one of 20 scheduled stops on the band's current 20th anniversary tour.

Since Café Tacuba came together in 1989, its popularity across Latin America has grown steadily. Along with such other rocken español pioneers as Los Fabulosos Cadillacs of Argentina, the band has continued to make records and mature with its audience, even while attracting twenty- and thirtysomething adherents. In recent weeks, it has played in Bolivia, Chile, Argentina and Cuba, and after L.A. it is scheduled to continue on to Colombia, Peru, Ecuador, London and Barcelona.