In Europe, he studied European rail systems and was inspired by the Swiss railroad which climbed Mount Righi with slopes of up to 20%, to run the railway extension to Petrópolis.

In the meantime he attended courses at the Sorbonne and the Collège de France, visiting factories, steel mills, transport companies and public works in Europe.

Appointed mayor by President Rodrigues Alves, Pereira Passos promoted a great urban reform in the city, with the goal of transforming it into a modern French-style capital, a "Tropical Paris".

[1] Inspired by the Haussmann reforms, in four years Pereira Passos transformed the city's appearance: the cortiços (high-density housing for low income people) and the narrow, dark streets, were demolished, with large boulevards and buildings took their place.

[4] Despite improvements in sanitation and urban development, Pereira Passos's plan entailed a high social cost, with the beginning of formation of favelas in the city.

As a result of these demolitions, the poor population of the city center was forced to live with other families, to pay high rents or to move to the suburbs, since the popular housing constructed to replace the demolished ones was insufficient.

A large part of the immense population affected by the remodeling remained in the region and the hills located in the center of the city - Providência, Santo António, among others - once little inhabited, suffer a rapid occupation of the proletarian housing.