Harmondsworth is a village in the London Borough of Hillingdon with a short border to the south onto London Heathrow Airport. The village has no railway stations however adjoins the M4 motorway and is bisected by its predecessor, the Bath Road. Harmondsworth is an ancient parish which once included the large hamlets of Heathrow, Longford and Sipson. Longford and Sipson have modern signposts and facilities as separate villages, remaining to a degree interdependent such as for schooling. Its great barn and its church are well-repaired medieval buildings in the village. The largest proportion of land in commercial use is related to air transport and hospitality. The village includes public parkland with footpaths and butts onto the River Colne and further land in its regional park to the west, within Colnbrook.
The west of the village has two major airline headquarters (international and local) and two immigration detention centres, including one for a maximum of 620 men without either adequate proof of right of entry to, or to remain in, the United Kingdom. Many international visitors stay within the bounds of Harmondsworth each year, in hotels branded as 'Heathrow' as the hamlet of Heathrow and the farm of Perry Oaks in the parish were absorbed by the airport and the term is applied to all hotels accessed from Bath Road in the borough.
Harmondsworth is one of the ancient parishes of Middlesex. From 1894 to 1930 it was part of Staines Rural District and from 1930 to 1949 it was part of Yiewsley and West Drayton Urban District. In 1949 all the parishes within Yiewsley and West Drayton Urban District were merged into the parish of Yiewsley and West Drayton. Since 1965 the former territory of Harmondsworth has been part of the London Borough of Hillingdon.