| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Op Linkebeek | city | Vlaanderen | Belgium | 50.77 | 4.35 | 295 | 199720 |
| Op Merlemont | city | Vlaanderen | Belgium | 50.88 | 5.40 | 141 | 28161 |
| Op Sint-Antonius Berg | city | Vlaanderen | Belgium | 50.87 | 5.62 | 242 | 42424 |
| Op de Baan Dries | city | Vlaanderen | Belgium | 51.03 | 5.17 | 127 | 30784 |
| Op de Berg | city | Vlaanderen | Belgium | 50.89 | 5.61 | 236 | 28903 |
| Op de Dieken | city | Vlaanderen | Belgium | 51.13 | 5.72 | 104 | 11959 |
| Op de Vlucht | city | Vlaanderen | Belgium | 51.05 | 5.07 | 101 | 27245 |
| Op den Beek | city | Vlaanderen | Belgium | 50.78 | 5.32 | 219 | 15511 |
| Op den Berg | city | Vlaanderen | Belgium | 51.08 | 5.68 | 150 | 4438 |
| Op het Root | city | Vlaanderen | Belgium | 50.85 | 5.58 | 301 | 21293 |
| Op-Aygem | city | Vlaanderen | Belgium | 50.90 | 3.93 | 127 | 33306 |
| Op-Velp | city | Vlaanderen | Belgium | 50.81 | 4.79 | 308 | 18621 |
| Opaaigem | city | Vlaanderen | Belgium | 50.90 | 3.93 | 127 | 33306 |
| Opbeek | city | Vlaanderen | Belgium | 50.80 | 4.22 | 196 | 70492 |
| Opbeek | city | Vlaanderen | Belgium | 50.80 | 4.22 | 196 | 70492 |
| Opbrakel | city | Vlaanderen | Belgium | 50.79 | 3.75 | 164 | 20291 |
| Opdorp | city | Vlaanderen | Belgium | 51.03 | 4.22 | 26 | 39631 |
| Opgeldenaken | city | Wallonie | Belgium | 50.71 | 4.84 | 328 | 9966 |
| Opglabbeek | city | Vlaanderen | Belgium | 51.04 | 5.58 | 213 | 16928 |
| Opgrimbie | city | Vlaanderen | Belgium | 50.94 | 5.68 | 141 | 45594 |
| Opgrimby | city | Vlaanderen | Belgium | 50.94 | 5.68 | 141 | 45594 |
| Ophain | city | Wallonie | Belgium | 50.67 | 4.35 | 403 | 47465 |
| Ophain | city | Wallonie | Belgium | 50.69 | 4.19 | 144 | 49270 |
| Ophain-Bois-Seigneur-Isaac | city | Wallonie | Belgium | 50.67 | 4.35 | 403 | 47465 |
| Ophalfen | city | Vlaanderen | Belgium | 50.87 | 4.19 | 101 | 54181 |
| Ophasselt | city | Vlaanderen | Belgium | 50.82 | 3.89 | 88 | 29045 |
| Opheers | city | Vlaanderen | Belgium | 50.74 | 5.30 | 341 | 17317 |
| Ophem | city | Vlaanderen | Belgium | 50.94 | 4.30 | 209 | 79733 |
| Ophem | city | Vlaanderen | Belgium | 50.83 | 4.65 | 206 | 44810 |
| Ophem | city | Vlaanderen | Belgium | 50.84 | 4.49 | 262 | 115157 |
| Ophem | city | Vlaanderen | Belgium | 50.83 | 3.93 | 131 | 18619 |
| Opheylissem | city | Wallonie | Belgium | 50.74 | 4.98 | 219 | 12603 |
| Ophoven | city | Vlaanderen | Belgium | 51.13 | 5.80 | 85 | 35200 |
| Ophoven | city | Vlaanderen | Belgium | 51.08 | 5.57 | 239 | 18963 |
| Ophoven | city | Vlaanderen | Belgium | 51.05 | 5.57 | 255 | 22536 |
| Opitter | city | Vlaanderen | Belgium | 51.12 | 5.65 | 141 | 10276 |
| Opleeuw | city | Vlaanderen | Belgium | 50.82 | 5.38 | 242 | 9359 |
| Oplinter | city | Vlaanderen | Belgium | 50.83 | 4.98 | 131 | 28167 |
| Oplombeek | city | Vlaanderen | Belgium | 50.81 | 4.12 | 226 | 30935 |
| Opoeteren | city | Vlaanderen | Belgium | 51.07 | 5.66 | 226 | 3391 |
| Opont | city | Wallonie | Belgium | 49.93 | 5.12 | 1158 | 2631 |
| Oppagne | city | Wallonie | Belgium | 50.31 | 5.51 | 1010 | 4964 |
| Oppem | city | Vlaanderen | Belgium | 50.94 | 4.30 | 209 | 79733 |
| Oppem | city | Vlaanderen | Belgium | 50.83 | 4.65 | 206 | 44810 |
| Oppem | city | Vlaanderen | Belgium | 50.84 | 4.49 | 262 | 115157 |
| Oppem | city | Vlaanderen | Belgium | 50.83 | 3.93 | 131 | 18619 |
| Opperbuesinghen | city | Vlaanderen | Belgium | 50.82 | 4.14 | 160 | 28669 |
| Opperbuizingen | city | Vlaanderen | Belgium | 50.82 | 4.14 | 160 | 28669 |
| Opperbuzingen | city | Vlaanderen | Belgium | 50.82 | 4.14 | 160 | 28669 |
| Opperstraat | city | Vlaanderen | Belgium | 50.87 | 4.09 | 101 | 65024 |
| Oppidum Sancti Trudonis | city | Vlaanderen | Belgium | 50.82 | 5.19 | 196 | 27432 |
| Opprebais | city | Wallonie | Belgium | 50.68 | 4.80 | 400 | 6678 |
| Oppuers | city | Vlaanderen | Belgium | 51.06 | 4.24 | 9 | 37302 |
| Oppum | city | Vlaanderen | Belgium | 50.92 | 5.20 | 127 | 17946 |
| Oppuurs | city | Vlaanderen | Belgium | 51.06 | 4.24 | 9 | 37302 |
| Oprode | city | Vlaanderen | Belgium | 50.73 | 4.37 | 396 | 88254 |
| Opsinnich | city | Vlaanderen | Belgium | 50.74 | 5.89 | 830 | 9400 |
| Opsmeer | city | Vlaanderen | Belgium | 50.97 | 3.95 | 65 | 42646 |
| Opstal | city | Vlaanderen | Belgium | 51.26 | 5.00 | 59 | 9224 |
| Opstal | city | Vlaanderen | Belgium | 51.25 | 4.90 | 52 | 36313 |
| Opstal | city | Vlaanderen | Belgium | 51.00 | 4.18 | 65 | 47419 |
| Opstal | city | Vlaanderen | Belgium | 50.90 | 3.77 | 183 | 19842 |
| Opstal Dries | city | Vlaanderen | Belgium | 51.01 | 4.03 | 9 | 53947 |
| Opstaldries | city | Vlaanderen | Belgium | 50.80 | 3.83 | 114 | 23990 |
| Opstalhoef | city | Vlaanderen | Belgium | 51.13 | 4.68 | 19 | 36587 |
| Opstalhoeve | city | Vlaanderen | Belgium | 51.13 | 4.68 | 19 | 36587 |
| Opvelp | city | Vlaanderen | Belgium | 50.81 | 4.79 | 308 | 18621 |
| Opvelpen | city | Vlaanderen | Belgium | 50.81 | 4.79 | 308 | 18621 |
| Opwijk | city | Vlaanderen | Belgium | 50.97 | 4.18 | 104 | 45770 |
| Opwinkel | city | Vlaanderen | Belgium | 51.17 | 5.71 | 101 | 12869 |
| Opwyck | city | Vlaanderen | Belgium | 50.97 | 4.18 | 104 | 45770 |
| Opzullik | city | Wallonie | Belgium | 50.65 | 3.92 | 269 | 7204 |