| Site name | Country | County | Nearest town | Site type | Access | Classification (girth in metres) | View on map |
|---|---|---|---|---|---|---|---|
| Castle Mary – Cloyne | Ireland | Co. Cork | Cork | historic site | Yes | Ancient 4m-5m | View On Map |
| Castle Upton | Ireland | Antrim | Templepatrick | historic site | Yes | Ancient 4m-5m | View On Map |
| Castle Ward | Ireland | Co. Down | Strangford/Downpatrick | planted avenue | Yes | Notable | View On Map |
| Castlecomer House | Ireland | Co. Kilkenny | Kilkenny | estate | Yes | Ancient 4m-5m | View On Map |
| Castlecoote – Fuerty | Ireland | Co. Roscommon | Roscommon | historic site | Yes | Ancient 4m-5m | View On Map |
| Castlegrove House Hotel | Ireland | Co. Donegal | Letterkenny | garden | Yes | Ancient 4m-5m | View On Map |
| Castlehyde | Ireland | Co. Cork | Cork | estate | Yes | Ancient 5m-7m | View On Map |
| Castlemorton | England | Worcestershire | Tewkesbury | churchyard | Yes | Lost | View On Map |
| Caterham | England | Surrey | Reigate | churchyard | Yes | Lost | View On Map |
| Cathedine | Wales | Powys | Brecon | churchyard | Yes | Ancient 5m-7m | View On Map |
| Catherington | England | Hampshire | Havant | churchyard | Yes | Lost | View On Map |
| Cattistock | England | Dorset | Dorchester | churchyard | Yes | Notable | View On Map |
| Catworth | England | Cambridgeshire | Huntingdon | churchyard | Yes | Notable | View On Map |
| Caversham Court | England | Berkshire | Reading | parkland | Yes | Ancient 4m-5m | View On Map |
| Cavigny | France | Manche - Normandie | Saint - Lô | churchyard | Yes | Ancient 4m-5m | View On Map |
| Cawdor Castle | Scotland | Highland | Nairn | garden | Yes | Notable | View On Map |
| Cawthorne – Barnsley | England | Yorkshire - South | Barnsley | churchyard | Yes | Lost | View On Map |
| Caynham | England | Shropshire | Ludlow | churchyard | Yes | Ancient 5m-7m, Notable | View On Map |
| Cefn Lla – Llanbadoc | Wales | Monmouthshire | Usk | footpath/road | Yes | Notable | View On Map |
| Cefnllys | Wales | Powys | Llandrindod Wells | churchyard | Yes | Ancient 5m-7m, Lost, Notable | View On Map |