The second book of 20th Century Tunja´s collection is dedicated to the first decades of the century, when there was the first phase of modernization from the implementation of public services to the adaptation of the streets to new locomotion forms, construction of new neighborhoods, and urban public facilities, associated with the celebrations of anniversaries. The chapters deal with: the first one adressess the transformation in the period; the second,  forms of urban growth; the third, the normative background; the fourth, infrastructures such as roads and railway lines; the fifth, the constructions from the anniversaries celebrated; the sixth, the provision of public household services; the seventh, public spaces: streets, sidewalks, parks, and squares; the eighth, public facilities and the ninth, the growth of neighborhoods and workers' housing.