Which African capital stands at the mouth of the Bou Regreg River? Rabat.
Rabat is Morocco's capital on the Atlantic coast. The Bou Regreg forms its northern edge and empties into the Atlantic between Rabat and the neighbouring city of Salé. Because the estuary is shared by the two cities, the clue points to Rabat as the capital rather than to Salé, which is also located at the river mouth.
The river is about 240 kilometres long and rises in Morocco's Middle Atlas region before crossing the country's central plateau. Its tidal estuary extends inland, and the river has historically supported transport, trade and settlement. The ancient ruins of Chellah stand near the mouth, on the Rabat side.
Rabat's historic landmarks include the Kasbah of the Udayas, the Hassan Tower and the Mohammed V Mausoleum. A common mistake is choosing Casablanca because it is Morocco's largest city; Casablanca lies farther south along the Atlantic coast and is not the national capital.