Ballymun is an outer suburb of Dublin, Ireland, at the northern edge of the Northside, the green-field development of which began in the 1960s to accommodate a housing crisis in inner city areas of Dublin. While the newly built housing was state-of-the-art at the time, comprising high-rise tower blocks and flat complexes, residents were moved in years before shops, schools and other infrastructure were fully ready, and the area became well known for both a strong community spirit and considerable social challenges. Ballymun has several sub-districts such as Sillogue, Coultry, Shangan and Poppintree, and is close to both the Republic of Ireland's only IKEA store and to Dublin Airport. The area is the source of one Dublin river, and parts lie in the floodplain of another, and there are a number of parks.

Dublin is the capital and largest city of Ireland. On a bay at the mouth of the River Liffey, it is in the province of Leinster, bordered on the south by the Dublin Mountains, a part of the Wicklow Mountains range. At the 2022 census, the city council area had a population of 592,713, while Dublin City and its suburbs had a population of 1,263,219, and County Dublin had a population of 1,501,500.