Take the ferry from Banjul and the first thing you see across the water is a low fort squatting at the river mouth, its cannon still pointing out toward the Atlantic. Fort Bullen guards the northern bank of the Gambia, in Barra, and it was built by the British in 1826 to keep watch on the slave ships that kept slipping past after Britain had outlawed the trade. The brick walls are modest and the guns are old, but the position says everything: whoever held this bank held the river, and the river was the Gambia's only real road into the interior.
It is part of the UNESCO listing that also covers Kunta Kinteh Island, the old James Island upriver, where the story of Alex Haley's Roots begins. You can read the two as a pair, one a fortress of capture and the other a fortress of suppression, a few hours apart on the same water. Small museum displays and a guide, when one is available, fill in the history, and the view from the ramparts across to Banjul's skyline is worth the entry alone.
For riders the real adventure is the crossing. Ferries run between Banjul and Barra, but the queue can swallow hours, and you board with trucks, market traders and cheerful chaos. Bring patience, water and small change. Barra itself is a town of about five thousand, loud with taxis and street stalls, and has fuel and simple places to eat grilled fish and rice. From here the main road leads north toward the Senegalese border at Amdallai and on toward the Saloum Delta, with flat, hot, mostly straight asphalt and the occasional pothole sized for a bucket.
The best season is November to February, when the harmattan has not yet turned the air to haze and the days are warm, not scorching. From June to October the rains turn the verges green and the roads slick. In the evenings the light on the river is soft and gold, fishing pirogues come in with their catch, and the breeze off the water carries woodsmoke, salt and frying oil. It is worth lingering until sunset.