On Independence Drive, the National Museum has a modest but well-curated collection covering the country's history, ethnography, and the slave trade. It is not large, but the exhibits on Gambian peoples and the transatlantic slave trade give useful context for visits to Kunta Kinteh Island and Juffure. Entry is cheap and the staff are helpful.
National Museum of The Gambia
Small museum with context on the slave trade and Gambian peoples