The city plan created by Pedro Arrieta in 1737 was not the first or the best map of the colonial capital city, although it was the one used for the construction of the sewage system, open channels and other clearing works for the city. Viceroy Revillagigedo used it to increase the taxes of all the urban properties. "There were street vendors invading the Main Plaza and all the plazas, there were channels from Xochimilco and in the bridges there were selling food and other products, it was a dirty city"--P. 41 comments architect Luis Ortiz Macedo, who rescued the late art historian Francisco de la Maza's (1913-1972) unedited notes and has published the most updated and complete study of the noted colonial city plan, complemented with notes and documentation from different archives, period plans from other cities, illustrations and diverse bibliographic sources.