| Site name | Country | County | Nearest town | Site type | Access | Classification (girth in metres) | View on map |
|---|---|---|---|---|---|---|---|
| Mariners Hill – nr Westerham | England | Kent | Sevenoaks | field | Yes | Ancient 4m-5m | View On Map |
| Mark | England | Somerset | Bridgwater | churchyard | Yes | Lost | View On Map |
| Market Bosworth – Bosworth Hall | England | Leicestershire | Leicester | garden | Yes | Ancient 4m-5m | View On Map |
| Market Harborough | England | Leicestershire | Leicester | garden | Yes | Ancient 4m-5m | View On Map |
| Markwells Wood | England | Hampshire | Horndean | woodland | No | Ancient 5m-7m | View On Map |
| Marlay Park – Rathfarnham | Ireland | Dublin | Dublin | estate | Yes | Ancient 5m-7m | View On Map |
| Marldon | England | Devon | Torquay | churchyard | Yes | Notable | View On Map |
| Marston Bigot | England | Somerset | Frome | former religious site | No | Ancient 7m+ | View On Map |
| Marston Montgomery | England | Derbyshire | Uttoxeter | churchyard | Yes | Notable | View On Map |
| Marston St.Lawrence | England | Northamptonshire | Banbury | churchyard | Yes | Ancient 5m-7m | View On Map |
| Martigny – sur – l’ Ante | France | Calvados - Normandie | Falaise | churchyard | Yes | Ancient 7m+ | View On Map |
| Martin | England | Hampshire | Salisbury | churchyard | Yes | Notable | View On Map |
| Martindale | England | Cumbria | Penrith | churchyard | Yes | Ancient 5m-7m | View On Map |
| Martley – Hillside | England | Worcestershire | Worcester | garden | No | Notable | View On Map |
| Martock | England | Somerset | Yeovil | churchyard | Yes | Ancient 4m-5m | View On Map |
| Matching | England | Essex | Harlow | churchyard | Yes | Notable | View On Map |
| Mathern | Wales | Monmouthshire | Chepstow | churchyard | Yes | Lost | View On Map |
| Mathon | England | Herefordshire | Great Malvern | churchyard | Yes | Ancient 5m-7m | View On Map |
| Matson | England | Gloucestershire | Gloucester | churchyard | Yes | Ancient 4m-5m | View On Map |
| Maxey | England | Cambridgeshire | Peterborough | garden | No | Notable | View On Map |