Hello Kelly
As the others have already indicated there is a location called Castle Mill in Ashley in Cheshire. Very close to Casrle Mill - there was a Mill there - there is a Castle Hill Farm.
A dew years ago now I belonged to an archaeology group. It was suggested that we ought to have a look at a particular location near to the Farm on the height above it. Your relative would appear to be related to the 'castle' - what ever the structure then - in the sixteenth century. when something may well have been standing.
I was led to believe that the University of Manchester archaeologists (GMAU) may have had an interest.
If you try this map site
http://maps.cheshire.gov.uk/tithemaps/Use Place Search to go to Ashley, (parsih of Bowdon). This will hive you all the Plots in Ashley. If you go to Plots 216 or 217 you should find thereabouts Castle Hill Farm. If you use Twin Maps and look also at say the 1910 map you should
be able to relate it to where it is in Cheshire,
My apologies if you have already done that

Best wishes
Reiver