| Name of the place | CERL ID of a place | Country | Longitude | Latitude | |
|---|---|---|---|---|---|
| Nyköping | cnl00012370 | Sweden | 17.0 | 58.75 | |
| Nyon | cnl00002826 | — | 6.23861111111111 | 46.3819444444444 | |
| Nyons | cnl00012372 | France | 5.13305555555556 | 44.3602777777778 | |
| Oberhausen | cnl00024768 | — | — | — | |
| Oberholzheim | cnl00020194 | Germany | — | — | |
| Oberkammlach | cnl00042456 | Germany | 10.4205555555556 | 48.0472222222222 | |
| Oberkich | cnl00018860 | Germany | — | — | |
| Obernai | cnl00019716 | France | 7.48 | 48.46 | |
| Oberramstadt | cnl00019819 | Germany | 10.4380555555556 | 49.3291666666667 | |
| Oberursel | cnl00004803 | Germany | 8.58305555555556 | 50.2 | |
| Oberwiesenthal | cnl00032594 | Germany | — | — | |
| Ocaña | cnl00025420 | Colombia | — | — | |
| Ochsenfurt | cnl00012447 | Germany | 10.08 | 49.6494444444444 | |
| Ockham | cnl00019540 | — | — | — | |
| Oddington | cnl00023840 | England | — | — | |
| Odense | cnl00012456 | Denmark | 10.38 | 55.4 | |
| Odessa | cnl00012459 | — | 30.73 | 46.4697222222222 | |
| Odos | cnl00019835 | France | 0.0586 | 43.1969 | |
| Oederan | cnl00025000 | Germany | — | — | |
| Oegstgeest | cnl00016324 | Netherlands | 4.46666666666667 | 52.1830555555556 | |
| Oehringen | cnl00032829 | Germany | 9.5 | 49.2 | |
| Oettingen | cnl00012469 | Germany | 10.6 | 48.95 | |
| Ofen | cnl00012470 | Germany | 10.58 | 47.7 | |
| Offenbach | cnl00019774 | Germany | 8.76972222222222 | 50.1 | |
| Offenbach am Main (Hessen) | cnl00019774 | Germany | 8.76972222222222 | 50.1 |