Ancient trees present structural and functional characteristics fundamental for sustaining complex and unique assemblages of species. They are a resource globally threatened by both intensive land uses and lack of recruitment. Their disappearance would involve not only the loss of majestic organisms with high intrinsic value, but may also result in the disappearance of rare and endangered species. Italy is currently implementing a new list of noteworthy ancient trees (i.e. monumental trees) and the preliminary results of this new inventory have been analysed as a case study of a national initiative. The provisional list included 950 complete records, corresponding to 65 genera and 118 species. The most abundant species was Quercus pubescens Willd while the most common genera were Quercus, Larix, Cedrus, Fagus and Platanus. Age and size were the most used criteria for inclusion of trees in the census. The fundamental novelty of the new inventory is that it is based on a set of well-defined criteria of monumentality and that it clearly recognised the ecological value of ancient trees. Preserving a tree for its ecological role requires a profound cultural shift. The value of microhabitats, structures that have historically been considered defects, should be recognised and managed accordingly. Ancient trees are often part of disappearing cultural landscapes: to preserve the richness and diversity of these habitats, new policies and regulations are needed. The preservation of landscapes, where there is still a high density of ancient trees, should be a priority for all European countries in order to conserve their unique associated fauna and for their irreplaceable functional value for biodiversity conservation.