Roving bands of musicians chased down cars on one of the city's busiest avenues, leaning into windows to bargain over the price of a song. Black-clad musicians in cowboy boots then assembled ragtag groups that played out of tune while singers hoarsely belted out mournful ballads about love and heartbreak.
The aching music may remain one of Mexico's top cultural exports, by which the country is known worldwide, but its fortunes have fallen in its homeland, with few well-trained musicians and few decent venues to play in.
A new mariachi school in Mexico City is seeking to revive a music that's lost ground over the years and that sometimes seems relegated to commercial jingles and elevator Muzak. Called the Mariachi School Ollin Yoliztli, meaning life and movement in indigenous Nahautl, the school teaches folk bands how to play professionally while grooming a new generation of songwriters and composers.
"What this school will do is dignify mariachi music," said director Leticia Soto.
Housed in a former nightclub on the plaza, it's Mexico's first professional school dedicated to the genre. Eventually, Soto said, she hopes to offer Mexico's first university-level degree in the music. Another school in the western state of Jalisco, the birthplace of mariachi, offers workshops but not a degree.
The goal is to formalize a music that has largely been passed down among the generations, without formal instruction. Last year, UNESCO recognized mariachi as an Intangible Cultural Heritage of Humanity, and the city has tried to protect that heritage by both cleaning up the plaza and helping set up the school.
Most of the more than 2,000 musicians who ply their trade at the newly renovated colonial plaza learned to play traditional favorites such as "Cielito Lindo" and "Guadalajara" from their parents or other relatives. Most of the players there can't read music and run through the songs by ear.
Miguel Martinez remembers a different time. The 91-year-old began playing the trumpet 78 years ago in the Plaza Garibaldi, when there were only five mariachi groups working there, with only two including trumpet.
He joined the Mariachi Vargas de Tecalitlan, Mexico's top ensemble, in 1940, when the music was featured almost daily on the radio. Hundreds also packed the Blanquita Theater for shows that included some of the top singers of ranchera, another, more guitar-based genre.
"It makes me very sad to see what these mariachis have done to the music that el Mariachi Vargas did so much to honor," Martinez said. "The truth is that I would leave this world very happy if I could see that our folklore will continue, because we were losing it."
With that in mind, he called the school "a fantastic idea and something that authorities should have done a long time ago."
For guitarist Arlette Gudino, one of a dozen women accepted at Ollin Yoliztli, playing mariachi music is a passion passed down by her trumpet-playing great-grandfather.
"There are places outside of Mexico where people get more excited to listen to mariachi than here," said the 23-year-old actress. "I would like to do something to get people to value the musical treasure we have."
The 102 members of the first class range from a 14-year-old junior high school student to a 68-year-old retired nurse. They started school last week and are scheduled to graduate in three years with a technical degree.
During that time, they'll learn music theory and mariachi history and be taught how to sing as well as play the trumpet, guitar, violin and the round-backed guitar called the vihuela.
Trumpet player Raul Rosas, 38, who waits in the plaza for clients, admitted he and the other musicians there could use some training.
"We all should go that school because we don't play the music like it should be played," said Rosas, one of nine brothers who play in mariachi bands. "We're musicians who play by ear, why fool ourselves?"
The first mariachi bands, in the 18th century, played only stringed instruments and dressed in white cotton fabric, huarache sandals and wide-brimmed straw hats — the clothing of Mexican farm workers of the time.
Trumpets were added in the early 20th century, and mariachi bands began wearing the more elegant charro, or cowboy, outfits familiar to modern audiences: a short, embroidered jacket, snug-fitting pants with shiny buttons along the legs, fluffy bow ties and the iconic wide-brimmed sombreros.
By the mid-20th century, mariachi music had become a widely popular symbol of Mexican culture, played by radio stations and featured in charro films during the country's Golden Age of cinema, from 1935 to 1959. By then, the music had become popular in Central and South America and the United States.
The 1980s saw the genre fade as radio buzzed with more commercially successful music such as norteno and banda, which includes lyrics about drug trafficking, or pop music.
Now, few hit songs are done in the mariachi style, and only a handful of places in this metropolis of 20 million feature live, professional mariachi bands.
The genre's absence in the mass media and intellectual circles also contributed to its decline, said anthropologist Jesus Jauregui, the top expert on the music in Mexico.
"The place mariachi bands get in movies nowadays is not very dignified because they are usually second-rate characters who are accompanying the singer," Jauregui said. "Another factor is the contempt with which the Mexican intelligentsia treats mariachi. No historian or sociologist, musicologist or folklore expert has done studies on mariachi music."
Nonetheless, mariachi retains deep roots in Mexican culture, with many people knowing by heart longtime favorites. Almost every big event in Mexico, from weddings and funerals to Mother's Day celebrations, includes a mariachi band, and abroad, the music offers a tie for many Mexicans to their native land. Most of that music is amateurish at best.
The handful of top mariachi stars left can nonetheless still fill auditoriums in Mexico, and fans can catch the best mariachi at occasional festivals.
"In the United States, the music is viewed with more respect and that has to do with the fact that they teach it in junior high schools and in high schools and that doesn't happen in Mexico," Jauregui said.
Soto's school has tried to turn that around by hiring some of the best musicians in the business, including former members of the group Mariachi Vargas de Tecalitlan, which continues to tour worldwide, often performing with classical orchestras and symphonies.
If anything, the market has shown it'll pay more for higher quality mariachi, said Victor Lemus, 44, who has played violin with Los Emperadores in Plaza Garibaldi for the last 22 years.
Many in the 14-member ensemble have taken private music classes, and they practice twice a week. That lets them charge twice the average rate of $8 (100 pesos) per song for bands with six members.
Still, on a recent night, none of the Mexican and foreign revelers dancing to the energetic two-step rhythms at the plaza seemed to mind that most of the bands lacked polish, instead requesting songs until they ran out of money or energy.
"Most mariachis right now just put on the charro suit and go out to the street to play and they forget that after the flag, the mariachi is what best represents Mexico," Lemus said. "But if the new generations learn to play it like it should be, they will ennoble the music."