| Site name | Country | County | Nearest town | Site type | Access | Classification (girth in metres) | View on map |
|---|---|---|---|---|---|---|---|
| Illeville-sur- Montfort | France | Eure - Normandie | Rouen | churchyard | Yes | Ancient 4m-5m | View On Map |
| Ilston | Wales | Glamorgan | Swansea | churchyard | Yes | Ancient 5m-7m | View On Map |
| Inchbrakie – nr Crieff | Scotland | Perth and Kinross | Perth | historic site | No | Notable | View On Map |
| Inchlonaig | Scotland | Argyll and Bute | Luss | woodland | No | Notable | View On Map |
| Inkpen | England | Berkshire | Hungerford | churchyard | Yes | Notable | View On Map |
| Innesfallen Island | Ireland | Co. Kerry | Killarney | historic site | Yes | Notable | View On Map |
| Ipsden Heath – Checkendon | England | Oxfordshire | Wallingford | woodland | Yes | Notable | View On Map |
| Ipswich – Christchurch Park | England | Suffolk | Ipswich | parkland | Yes | Ancient 4m-5m | View On Map |
| Irby upon Humber | England | Lincolnshire | Grimsby | garden | No | Notable | View On Map |
| Irthing Gorge – Gilsland | England | Northumberland | Haltwhistle | cliff | Yes | Ancient 4m-5m | No Map Data |
| Itchen Abbas | England | Hampshire | Winchester | churchyard | Yes | Ancient 7m+ | View On Map |
| Itchen Wood | England | Hampshire | Winchester | woodland | Yes | Ancient 4m-5m | View On Map |
| Itchingfield | England | Sussex - West | Horsham | churchyard | Yes | Notable | View On Map |
| Itton | Wales | Monmouthshire | Chepstow | boundary | No | Ancient 4m-5m | View On Map |
| Ivington – Chipps House | England | Herefordshire | Leominster | garden | Yes | Notable | View On Map |
| Iwade | England | Kent | Sittingbourne | churchyard | Yes | Notable | View On Map |
| Iwerne Minster | England | Dorset | Blandford Forum | churchyard | Yes | Ancient 7m+ | View On Map |
| Jay’s Copse – Haslemere | England | Surrey | Haslemere | woodland | No | Ancient 4m-5m | View On Map |
| John of Gaunt’s Deer Park | England | Hampshire | Romsey | historic site | No | Ancient 4m-5m | View On Map |
| Jumièges Abbey | France | Seine-Maritime - Normandie | Rouen | former religious site | Yes | Notable | View On Map |