Cambridgeshire, to the south west by Bedfordshire, to the west by Northamptonshire and Rutland and to the north by Lincolnshire.
The historical county town was Huntingdon.
Note. Huntingdonshire is no longer a county, having been relegated to Local Government District status within moderrn Cambridgeshire. Huntingdonshire's historical archives are mostly manged by Cambridgeshire County Council and held at Huntingdon Library and Archives.
For additional information see Wikipedia and GENUKI:Huntingdonshire
A map of Huntingdonshire parishes is available from GENUKI.