For travel to Pobe, Porto-Novo and Cotonou, go to the main taxi station in town. The best time to travel is early in the morning when taxis leave more frequently. If leaving later, it is best to go to the 'Calvaire' about two kilometers north of town on the road to Cotonou, where you can board taxis already on their way.
If you are heading towards Bohicon or Abomey, leave from the station directly behind the Royal Palace. Note that vehicles leave quite infrequently from here, so the wait can be quite long.
For travel closer to Ketou, it is best to hire a moto-taxi that will take you to your destination and back.
