This original fair takes place every May first ever since 1965 in Otumba, State of Mexico, located 55kms northeast of Mexico City. The town (set in a semi-arid valley surrounded by nopales and century plants) by means of this fair renders cult to this noble animal who has accompanied man in his chores from time immemorial. Aside from the fair and at a distance of 25 kms, one of the most outstanding aqueducts in Mexico , perhaps in the entire world can be found and a visit here should notbebypassed. "The arches of Father Francisco de Tembleque", in honor of its architect, orginally was 34 km long of which only remains a stretch supported by 66 arches crossing a depression 39 mts high and 1 km. long.