On some of my first trips around Sao Paulo after moving here, I caught glimpses of life under the city’s many highway viaducts, whether it was of people storing recyclable waste or even living under the bridges. I refer to my roaming excursions in this city as “trips,” because this massive city of nearly 20 million inhabitants is a world in itself.

The shadow of aspiring boxer Laercio is projected on a wall as he uses a discarded truck axle for weight training at a gymnasium under the Alcantara Machado viaduct in the Mooca neighborhood of Sao Paulo, March 28, 2011. REUTERS/Nacho Doce

One day, as I gradually widened my geographic range and knowledge of my new city, I spotted people practicing sports under one bridge. It was a brief view but long enough to register in my mind. So when I read soon after about a boxing school under a viaduct and went to search it out, I realized immediately it was the same one I had spotted that day.

Aspiring boxers train at a gymnasium under the Alcantara Machado viaduct as cars drive past in the Mooca neighborhood of Sao Paulo, March 28, 2011.  REUTERS/Nacho Doce

Aspiring boxer Laercio (R) trains with his coach Mauricio Cruz at a gymnasium under the Alcantara Machado viaduct in the Mooca neighborhood of Sao Paulo, March 14, 2011. REUTERS/Nacho Doce

Under the bridge I met former pro boxer Nilson Garrido, the founder and owner of the school. Six years ago Garrido started a project in which he created several boxing academies under the viaducts of Sao Paulo. His goal was to take the sport to the poor and marginalized population. In the meantime the project attracted other people who started to contribute a small monthly fee for the use of the gym.

Brazilian former pro boxer Nilson Garrido slugs a discarded truck tire with a baseball bat inside his boxing gymnasium under the Alcantara Machado viaduct in the Mooca neighborhood of Sao Paulo, March 15, 2011. REUTERS/Nacho Doce

The Boxing Academies of Garrido adopt primitive training equipment that he developed himself during his years as a coach; plastic containers turned into punching bags, heavy rocks used for weightlifting and abdominal workouts, vehicle motor shafts for exercise bars, truck tires as weights for resistance training.

Aspiring boxer Chibata uses a truck shock absorber to strengthen his upper body during a training session at a gymnasium under the Alcantara Machado viaduct in the Mooca neighborhood of Sao Paulo, March 28, 2011. REUTERS/Nacho Doce

Aspiring boxers (L-R) Chibata and Valdir Aparecido (nicknamed "Gorilla"), punch a discarded refrigerator during a training session at a gymnasium under the Alcantara Machado viaduct in the Mooca neighborhood of Sao Paulo, March 28, 2011. REUTERS/Nacho Doce

Aspiring boxer Chibata uses a rock for abdominal exercises during a training session at a gymnasium under the Alcantara Machado viaduct in the Mooca neighborhood of Sao Paulo, March 28, 2011. REUTERS/Nacho Doce

Today Garrido manages and lives in the academy under the Alcantara Machado viaduct, part of which receives donations of more modern sports equipment, and where they are developing other activities besides boxing, such as gymnastics, skating and biking. The ring is located under a section of the overpass that doubles as a parking lot.