The history of observatories as organised structures starts with astronomical observatories and their development from the XVth century. Astronomical observatories bring together experimental techniques and practices from laboratories and adapt them to the observatory and field tradition, contributing to the transfer of practices ^[1][2].

Different types of observatories have been developed to improve the collection, coordination, and sharing of information on various scientific topics. For instance, National Museums of Natural History gather collections of flora, fauna, minerals, and fossils and provide essential information on present and past biological diversity ^[3]. More recently, at the international level, the Group on Earth Observations Biodiversity Observation Network (GEO BON) has been created as a “global network of researchers dedicated to improving the acquisition, coordination, and delivery of biodiversity information at the global, regional, and national levels”. As stated in its latest strategic plan, “data gathered through biodiversity monitoring are essential inputs into the science of detecting change in different dimensions of biodiversity, from genes to ecosystems. Trends in the gains and losses of these different dimensions of biodiversity are poorly estimated for most regions and not linked to their causes” ^[4]. GEO BON connects the national and regional Biodiversity Observation Networks as well as thematic networks (marine, freshwater, soil, or biomolecular biodiversity) to understand how biodiversity is changing and to generate indicators used by decision-makers to estimate progress towards the international goals and targets for biodiversity. NEON (the US National Ecological Observatory Network), supported by the U.S. National Science Foundation, is a continental-scale observation facility collecting long-term open-access ecological data to better understand the complexities of the Earth’s ecosystems and how they are changing. It is driven mainly by the scientific community to address a “very broadly based, general research question—what is the pace and nature of biological change” ^[5], depending on human actions with regional, national, or global causes or effects. NEON is designed to allow the scientific community to address, on a regional or continental scale, the major areas in environmental sciences considered as grand challenges by the National Research Council because they represent environmental issues of importance to humankind ^[6]. They concern biodiversity, biogeochemical cycles, climate change, ecology, and evolution of infectious diseases, invasive species, and land and habitat use. NEON provides open data, samples, and infrastructure to understand changing ecosystems over a period of 30 years ^[7]. From its inception, NEON has been expected to allow for the assessment of potential ecosystem responses to environmental changes and to forecast the effects of alternative environmental policies and actions.

These existing networks of observatories targeting the understanding of the various dimensions of environmental changes have inspired the creation of HealthDEEP (Health, Disease Ecology, Environment, and Policy), an international research unit under the auspices of CNRS (French National Centre for Scientific Research), Mahidol University, and Kasetsart University, based in Thailand, Bangkok, and Kanchanaburi. HealthDEEP constitutes a model of One Health Observatory integrated into the scientific and institutional international and regional landscapes.