There may be bakeries with pastries that are just as good or even better than those sold at Pasteleria Ideal, but tradition and atmosphere practically dictate that you should take an obligatory spin through the Ideal first.
This massive bakery (two floors at this particular location in the Centro Histórico) has been turning out Mexico's favorite baked goods since 1927. If you're not sure where to start among the racks and display cases loaded with trays of delectable pastries, try some classics: the shell-shaped concha,orejas (akin to palmiers), or the hilariously named pierna de pollo ("chicken's leg"-so named because of their shape), which might be filled with a fruit preserve or cream.
And even if you don't intend to purchase one, head to the second floor to see the bakery's other specialty: massive cakes. Whether for a quinceañera celebration, an Independence Day party, or a just-because occasion, Pasteleria Ideal makes some of the most ambitious-looking and entertaining cakes you've seen beyond reality TV.