The theme of environmental education, present in current political and cultural thinking, has distant and deep roots in the history of education and schooling. In addition to the contribution of the classics of pedagogical thought on the education-nature relationship, the early twentieth century saw the development of open-air schools, educational institutions aimed at a population of poor health, in which pedagogical innovations of outdoor education and outdoor learning, with a strongly interdisciplinary character, were initiated. Such experiences of open-air schools have been crucial as places of experimentation of long-lasting teaching practices throughout Italian school history, inherited and legitimized in elementary school curricula even after World War II, and increasingly declined in terms of environmental and sustainability education from the mid-1980s to the current regulations, embedded in an international framework that connects environmental knowledge and protection with global citizenship education.