Ossulstone is an obsolete subdivision (hundred) covering 26.4% of – and the most metropolitan part – of the historic county of Middlesex, England. It surrounded but did not include the City of London and the area has been entirely absorbed by the growth of London. It now corresponds to the seven London Boroughs of Inner London north of the Thames and, from Outer London, in decreasing order, certain historic parishes of the London boroughs of Ealing, Brent, Barnet, and Haringey.

Tyburn was a manor (estate) in the county of Middlesex, England, one of two which were served by the parish of Marylebone. Tyburn took its name from the Tyburn Brook, a tributary of the River Westbourne. The name Tyburn, from Teo Bourne, means 'boundary stream'.