| Lompnieu | |
| Arrondissement: | Belley |
| Canton: | Plateau d'Hauteville |
| Insee: | 01221 |
| Postal Code: | 01260 |
| Coordinates: | 45.9617°N 5.6608°W |
| Elevation M: | 650 |
| Elevation Min M: | 524 |
| Elevation Max M: | 1241 |
| Area Km2: | 11.35 |
| Population: | 134 |
| Population Date: | 2021 |
| Population Footnotes: | [1] |
Lompnieu is a former commune in the Ain department in eastern France. On 1 January 2019, it was merged into the new commune Valromey-sur-Séran.[2]
It is located in La Val Romey, which means, "The Roman Valley." The Romans built several outposts in the valley.
Lompnieu is located near the base of the large valley, with forest mounting on one side, and a plain with larger mountains looming on the other side. On a clear day, the snow-covered Alps can be seen. Lompnieu is around 600 metres in elevation. The climate is rather hot in the summer, attaining into the 1990s, and fairly cold in winter, with several large snow falls.