The Irish state has officially approved the following list of national monuments in County Monaghan. In the Republic of Ireland, a structure or site may be deemed to be a "national monument", and therefore worthy of state protection, if it is of national importance. If the land adjoining the monument is essential to protect it, this land may also be protected.
National Monuments
edit| NM# | Monument name | Description | Image | Townland | Location |
|---|---|---|---|---|---|
| 111 | Clones Round Tower | Round Tower |  | Crossmoyle | 54°10′41″N 7°13′52″W / 54.178041°N 7.231036°W |
| 112 | Clones High Cross | High Cross |  | Crossmoyle | 54°10′46″N 7°13′57″W / 54.179470°N 7.232628°W |
| 111 | Clones Church | Church |  | Crossmoyle | 54°10′41″N 7°13′52″W / 54.178041°N 7.231036°W |
| 382 | Mannan Castle | Castle (Motte & Bailey) |  | Donaghmoyne | 54°00′33″N 6°41′57″W / 54.009249°N 6.699125°W |
| 208 | Inishkeen Glebe Round Tower | Round Tower |  | Inishkeen Glebe | 54°00′13″N 6°34′44″W / 54.00368°N 6.578758°W |
| 564 | Mullyash Kerbed Cairn | Kerbed cairn |  | Mullyash, Tavanaskea | 54°10′27″N 6°40′10″W / 54.174201°N 6.669410°W |
| 367 | Cairnbaine | Court Tomb | Tiredigan | 54°11′50″N 7°04′29″W / 54.197304°N 7.074721°W |