Situated in the northernmost part of Kent, and covering an area of 23.99 km2, the parish is bounded on the north side by the River Thames, and in the east by the course of Yantlet creek, now silted up.

Avery Farm is on the tip of a promontory, which, in Anglo-Saxon times, is believed to have been an island in its own right, belonging to a woman named "Heahburh".

[7] It is thought she may have been an abbess, given that lands named after her were granted by the 7th century King Cædwalla of Wessex to the monastery at Medeshamstede, now known as Peterborough, presumably together with Hoo St Werburgh.

After the First World War, Kent and London county councils proposed to transform Allhallows into a major seaside resort, after the fashion of Victorian Herne Bay.

Other features include: zoological gardens, yachting centre, physical training stadium, the largest swimming pool in the country with artificial waves, holiday camp and 5,000 houses, up to date hotels, restaurants, theatres and cinemas.

There is now a holiday park that includes a 9-hole golf course, fresh water fishing lake, and a small entertainments complex with both indoor and outdoor pool.

This park is operated by Haven Holidays, owned by Bourne Leisure Ltd.[10] A large 1930s style pub, the British Pilot, was built, superseding the village inn, the Rose and Crown Tavern, now a dwelling.

Proposals made by Lord Foster in November 2011 to expand the transport system of south east England, called the Thames Hub, planned a new river barrier and road crossing and a shipping and rail complex.