[1] During his time in Córdoba Thays became infatuated with the young country and decided to spend the rest of his life in Argentina.

One of Thays' largest undertakings was the Parque Tres de Febrero,[2] a sweeping area of open land covering several square kilometers filled with thousands of trees, flowers, many fountains, and monuments in the barrio of Palermo.

A pet project of his was the Buenos Aires Botanical Garden,[1][2] for which he petitioned the city government to set aside land (almost 8 hectares), which he designed in sections to display plants organised by continent, with a large section devoted to the native plants of Argentina,[2] which were ignored in garden-making at the time.

[1] Thays worked most extensively in Buenos Aires precisely at a period in the city's history where it was growing extremely fast as a result of immigration, especially from Spain and Italy.

[4] Next to the Perito Francisco Moreno and other prominent figures founded July 4, 1912 Boy Scouts Association of Argentina.