According to the Annals of Inisfallen, Caill Tomair, a sacred wood dedicated to the North Germanic god Thor, was cut down under the orders of the Irish king Brian Boru when he conquered the Norse-Gaelic city of Dublin in the year 1000 CE. Sacred trees are powerful symbols across different cultures, and therefore were often targeted by rivals. In Irish folklore, many types of trees are venerated due to their associations with ancient monuments or because they are seen as the abode of particular nature spirits called faeries or ‘little people’. Trees are a valuable heritage: they form part of our history, culture, religion and society. Moreover, within urban landscapes, they make a significant contribution to people’s health and quality of life: they clean the air, provide natural, flood defences, mask noise and promote a general sense of wellbeing. That is why the Dublin City Tree Strategy set out a vision for the management of public trees in a long-term plan and also creates greater awareness of this valuable resource.