There was a time there when the inhabitants of Mexico City ruled their lives in accordance with the ringing of the Cathedral bells. The east tower has 18 bells, of which 3 are small ones used on feast days. All are casted in gold, silver and bronze. The west tower has ten bells, 3 are clock bells and 7 are manual, and it contains the main bell of the Cathedral -"Our Lady of Guadalupe"- weighing 20 tons and casted in 1762 in Ixtlahuaca.