| Country: | Wales |
| Official Name: | Plas Llanfair |
| Coordinates: | 53.2184°N -4.1992°W |
| Cardiff Distance Mi: | 127.6 |
| Cardiff Distance Km: | 205.4 |
| London Distance Mi: | 208.5 |
| London Distance Km: | 335.5 |
| Community Wales: | Llanfair Pwllgwyngyll |
| Unitary Wales: | Anglesey |
| Constituency Welsh Assembly: | Ynys Môn |
| Constituency Westminster: | Ynys Môn |
| Post Town: | Llanfair Pwllgwyngyll |
| Postcode District: | LL61 |
| Os Grid Reference: | SH 5326 7130 |
Plas Llanfair is a former country estate and mansion in the community of Llanfair Pwllgwyngyll, Anglesey, Wales, which is 127.6 miles (205.4 km) from Cardiff and 208.5 miles (335.5 km) from London.[1]
The present house was built in the early 19th century. It served as a nautical training school in the second half of the 20th century and the site is now owned by the Ministry of Defence.[2] [3] [4]