About 20 kilometers south of the historic center of Mexico City is the unusual suburb of Xochimilco, which has been described as “the Venice of Mexico.” It is crisscrossed with canals, along which gondoliers use long poles to propel colorfully painted and flower bedecked boats conveying tourists, young lovers and entire families enjoying picnics.

As the flat bottomed boats (known as trajineras) travel the waterways, smaller crafts approach carrying vendors selling snacks, drinks and souvenirs or entertainers ranging from single musicians to entire mariachi bands. Even photographers drift by to record participants in the floating fiesta.

Xochimilco has been recognized as a tourist attraction since the 1920s, but it has its origins in the 13th century, when a nomadic tribe of Nahua Indians related to the Aztecs settled the area. They practiced a system of cultivation where crops were grown in the lake on small rafts of interwoven reeds covered with mud and water plants. As roots developed, the rafts became anchored to the lake bottom. The abundance of water and the fertility of the mud enabled the rafts (known as chinampas) to produce as many as seven crops per year. The method ensured a plentiful food supply for the Aztec empire.

During their conquest of Mexico in 1521, the Spanish targeted this important agricultural center. Bitter fighting ensued, but the Spanish eventually burned the town and began to drain the lake. The surviving canals are a only remnant of what was once a much larger system. But even they almost were lost.

In more recent times, freshwater springs that once fed the lake were successively diverted to supply water to Mexico City, and waste water from the city was sent into the canals. By the 1970s, the waterways were so contaminated that the chinampas could not be used for food cultivation, so local farmers turned primarily to flower production. To revitalize the chinampas, they scraped organic matter from the bottoms of the canals and harvested chilicastle, a shiny blue-green algae, from the surface of the water.

Fortunately, the Mexican government soon saw the value in saving Xochimilco as both an agricultural region and a tourist attraction, and it provided assistance to clean up the canals. In 1987, UNESCO declared Xochimilco a World Heritage Site.

Today, farmers again cultivate vegetables on the chinampas, although not on those adjacent to the tourist canals. In the summer, they grow lettuce, spinach and such local favorites as acelga and verdolaga, and in the winter, they grow flowers.

While in Xochimilco, visitors might want to see some other sights. Parroquia de San Bernardino is a fortress-like parish church built in 1590, making it one of the oldest in the country. The exterior has an interesting side portal showing Indian influence, and inside is a crucifix with a figure of Christ formed from maize stems in a typically Indian technique.

Capilla del Rosario is a chapel with an intricate lacelike stucco exterior. Across from it is Mercado de Xochimilco, a lively market that welcomes shoppers every day of the week.

Teatro de los Insurgentes is a circular building with a mosaic by Mexican artist Diego Rivera, depicting the history of the Mexican theater. And the world’s largest and most important private collection of works by Diego Rivera and his wife Frida Kahlo is housed at Museo Dolores Olmedo Patino, an 18th century hacienda located a few minutes from Xochimilco center.