Start at Fort Jesus when it opens, before the heat builds. The Portuguese-built fort has a museum, a courtyard and views across the old harbour.
Walk uphill into the lanes of Old Town. Look for the carved wooden doors, which show how wealthy a family was. Stop at a small cafe for coffee and halwa.
Finish at the market near Biashara Street for spices, kanga cloth and fresh fruit. A local guide can add history that signs do not cover.