Poços de Caldas City Hall. Poços de Caldas is a city and municipality in south-western Minas Gerais state, Brazil, in the microregion of the same name. Its estimated population in 2009 was 151,449 inhabitants. The city has thermal waters. Poços was founded in 1872. The region had been inhabited by the Cataguases Indians, who had been expelled from their lands by the "Bandeiras Unidas Paulistas", during their quest for gold. The place was first called Freguesia de Nossa Senhora da Saúde das Águas de Caldas. In 1874 it became a district of Nossa Sra. da Saúde de Caldas, belonging to Caldas. In 1875 it was elevated to the category of city. This became famous after the discovery of the hot water, which could be used for curing disease, and many important people began to visit the spa in search of the cures provided by the water.