This communication presents the situation regarding astronomical and archaeoastronomical heritage related to the World Heritage Convention through recent years up until today. Some parallel events and works were promoted strongly within the IAU–UNESCO Initiative during the International Year of Astronomy (2009). This was followed by a joint program by the IAU and ICOMOS—an official advisory body assisting the World Heritage Committee in the evaluation of nomination dossiers. The result of that work is an important publication by around 40 authors from 20 different countries all around the world: Heritage Sites of Astronomy and Archaeoastronomy in the Context of the UNESCO World Heritage Convention (Ruggles & Cotte 2010). A second volume is under preparation (2015). It was also accompanied by some initiatives such as the “Windows to the Universe" organisation and the parallel constitution of local “Starlight Reserves”. Some regional meetings studying specific facets or regional heritage in the field giving significant knowledge progresses also accompanied the global trend for astronomical heritage.

WH assessment is defined by a relatively strict format and methodology. A key phrase is “demonstration of Outstanding Universal Value” to justify the WH Listing by the Committee. This communication first examines the requirements and evaluation practices about of demonstrating OUV for a given place in the context of astronomical or archaeoastronomical heritage. That means the examination of the tangible attributes, an inventory of the property in terms of immoveable and moveable components and an inventory of intangible issues related to the history (history of the place in the context of the history of astronomy and cultural history). This is also related to the application to the site of the concept of integrity and authenticity, as regards the place itself and in comparison with other similar places (WH sites already listed, sites on national WH Tentative Lists, or other similar places in the region). The second issue of the communication is to give a glimpse of today's WH List, including some difficulties with listing and occasional failures, and trends and promising approaches.

This communication proposes a methodical approach trying to link the concept of “Windows to the Universe” to the uses of the Criteria defined by the World Heritage Convention (UNESCO 1972). The first issue is well advanced today after more than 10 years of active studies and preservation projects such as “Starlight Reserves” by specialists of astronomy, archaeoastronomy and environmental sciences. The second issue is related to a UNESCO Convention ruled by the WH Committee that has led to the recognition of around 1000 World Heritage sites over 40 years. The official booklet Operational Guidelines for the Implementation of the World Heritage Convention (latest edition 2015) (UNESCO 2015) summarizes conceptual ideas and methodological recommendations for WH nominations. In practice the WH Committee's decisions rely on the scientific and professional evaluation of each site by UNESCO's advisory bodies: ICOMOS for cultural heritage and IUCN for natural heritage.

The first goal of this presentation is to establish appropriate understanding of a very specific conceptual approach (Windows to the Universe) in the context of a very large UN Convention (the World Heritage List) related both to cultural and natural heritage in general. The second goal is to give a readable understanding of the WH requirements coming from the strict evaluation of the “Outstanding Universal Value” (OUV) of a given place, including the choice of WH Criteria expressing OUV with respect to the format of the Guidelines. Furthermore, and due to concepts coming from two very different fields, the communication aims to present a practical methodology in the case of a possible WH nomination: how to understand relationships between different classes of value and how to demonstrate OUV and justify the choice of Criteria for the place. Beyond potential WH projects, obviously limited in number, the communication tries to propose an efficient and general methodology for assessing the value and creating understanding of places having a “Windows to the Universe” facet.