In 1893, Deering took time off from his other duties to study painting in Paris under Zorn for an entire season. Throughout his life, Deering enthusiastically supported and championed the work of many living artists while also avidly purchasing hundreds of older, more obscure works along with many acknowledged masterpieces. By 1881, William Deering's business activities had shifted to Illinois, where some earlier investments had led to his founding the Deering Harvester Company. As it grew, he enlisted both his sons in running the company. Charles moved to Chicago, taking up permanent residence in Evanston and becoming the company's secretary. His father retired in 1901. In 1902, J. P. Morgan financed a deal that combined Deering Harvester and the company founded by Cyrus McCormick, along with several others, to form the International Harvester Company. Charles Deering became chairman of the board of the newly created company. He served in this capacity until 1910, when he retired. Deering devoted the rest of his life to art collecting and to the creation of several estates in the United States and Europe. Deering dreamed of creating an art center in Spain, and in 1910 he had the "Palau Maricel" built with the help of the artist Miquel Utrillo i Morlius in Sitges, a town just south of Barcelona. The building was connected by a bridge across the lane to a second building he purchased, which now houses the "Museu Maricel". A portrait of him by Catalan artist Ramon Casas i Carbó can be seen in the museum, which is open to visitors. The "Palau Maricel" is also open to visitors, but only in the summer. Deering's hope was that the complex would become a magnet for artists and artistic life, where people of many nations would come to make art and study. In addition, Deering's own large and many-sided collection of Spanish art and decorative objects would be on display. In the end, however, Deering abandoned much of this plan. Instead, much of his collection was given to the Art Institute of Chicago, while other works were transferred to his estate at Cutler, Florida. Beginning around 1890, the William Deerings began wintering in Florida, first around St. Augustine, and later in the vicinity of Miami. Visiting them, both Charles and his half-brother became deeply interested in South Florida. Around 1908, Charles purchased some 212 acres of land in Buena Vista. In 1910, he hired Clinton Mackenzie to design a Spanish-style villa for the property.