Off the huge central plaza is the lovely sixteenth-century church of San Bernardino, full on Sundays with a succession of people paying homage and leaving offerings at one of its many chapels; in the plaza itself there are usually bands playing or mime artists entertaining the crowds.
The floating gardens adjoining the suburb of Xochimilco offer an intense carnival atmosphere every weekend and are likely to be one of your most memorable experiences of the city. Considerable effort has been expended in recent years to clean up the canals and maintain the water levels that had been dropping here, so Xochimilco (“place of the flower fields” in Náhuatl) looks set to remain the most popular Sunday outing for thousands of Mexicans. It’s also the one place where you get some feel for the ancient city and its waterborne commerce, thriving markets and dazzling colour – or at least an idealized view of it. Rent any of the colourful boats and you’ll be ferried around miles of canals, continually harangued by women selling flowers, fruit and hot food from tiny canoes, or even by larger vessels bearing marimba players and entire mariachi bands who, for a small fee, will grapple alongside you and blast out a couple of numbers. The floating gardens themselves are no more floating than the Titanic: following the old Aztec methods of making the lake fertile, these chinampas are formed by a raft of mud and reeds, firmly rooted to the bottom by the plants. The scene now appears like a series of canals cut through dry land, but the area is still a very important gardening and flower-producing centre for the city. If you wander the streets of Xochimilco town you’ll find garden centres everywhere, with wonderful flowers and fruit in the market that enlivens the town centre for much of Saturday (though whether it’s healthy to eat food raised on these dirty waters is open to question).