| Site name | Country | County | Nearest town | Site type | Access | Classification (girth in metres) | View on map |
|---|---|---|---|---|---|---|---|
| Cascob | Wales | Powys | Presteigne | churchyard | Yes | Ancient 7m+, Lost | View On Map |
| Castillon | France | Calvados - Normandie | Bayeux | churchyard | Yes | Ancient 7m+ | View On Map |
| Castle Ashby | England | Northamptonshire | Northampton | churchyard | Yes | Lost | View On Map |
| Castle Caereinion | Wales | Powys | Welshpool | churchyard | Yes | Ancient 4m-5m, Ancient 5m-7m, Notable | View On Map |
| Castle Carlton | England | Lincolnshire | Louth | historic site | No | Notable | View On Map |
| Castle Cary | England | Somerset | Shepton Mallet | churchyard | Yes | Ancient 5m-7m | View On Map |
| Castle Eden Dene | England | Northumberland | Durham | upland | Yes | Ancient 4m-5m | View On Map |
| Castle Frome | England | Herefordshire | Bromyard | churchyard | Yes | Ancient 5m-7m | View On Map |
| Castle Hill – Tonbridge | England | Kent | Tonbridge | woodland | Yes | Ancient 4m-5m | View On Map |
| Castle Hill Wood – Glasshouse | England | Gloucestershire | Gloucester | field | Yes | Ancient 4m-5m | View On Map |
| Castle Huntly | Scotland | Perth and Kinross | Dundee | parkland | No | Ancient 4m-5m | 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 |