| Name of the place | CERL ID of a place | Country | Longitude | Latitude | |
|---|---|---|---|---|---|
| Oudenaarde | cnl00007027 | Belgium | 3.6 | 50.85 | |
| Ouderkerk aan den IJssel | — | Netherlands | 4.636111 | 51.932222 | |
| Oudewater | cnl00012605 | Netherlands | 4.88 | 52.03 | |
| Oudorp | — | Netherlands | 4.773611 | 52.633056 | |
| Oullins | cnl00018149 | France | 4.8083 | 45.715 | |
| Oulton | cnl00020386 | England | -1.451 | 53.749 | |
| Oulu | cnl00031701 | Finland | 25.4666666666667 | 65.0166666666667 | |
| Overijse | cnl00050720 | Belgium | 4.536389 | 50.775 | |
| Oviedo | cnl00012614 | Spain | -5.83 | 43.37 | |
| Oxford | cnl00012616 | England | -1.25 | 51.75 | |
| Oxford [non-CERL] | — | — | — | — | |
| Oyonnax | cnl00017332 | — | 5.66666666666667 | 46.25 | |
| Paddington | cnl00048813 | England | -0.176111111111111 | 51.5155555555556 | |
| Paderborn | cnl00006611 | Germany | 8.75 | 51.7197222222222 | |
| Padova | cnl00010359 | Italy | 11.88 | 45.42 | |
| Padova/Passau [non-CERL] | — | — | — | — | |
| Padstow (Cornwall) | cnl00021267 | England | -4.938 | 50.538 | |
| Pagani | cnl00045204 | Italy | 14.6133333333333 | 40.7513888888889 | |
| Pailhat (Auvergne) | — | France | — | — | |
| Paimio | cnl00049618 | Finland | 22.6866666666667 | 60.4566666666667 | |
| Painblanc | cnl00020743 | France | — | — | |
| Paisley | cnl00033548 | Scotland | -4.423636 | 55.846627 | |
| Palaestina | cnl00000554 | No country: false imprint | — | — | |
| Palaiseau | cnl00026991 | France | 2.25 | 48.7166666666667 | |
| Palencia | cnl00012630 | Spain | -4.53 | 42.02 |