The ruins of Qanbalu or Quanbalu are located on the west coast of the Tanzanian island of Pemba, part of the Zanzibar Archipelago. They lie close to the village of Ngagu at the end of a long narrow peninsula known as Ras Mkumbuu, which lies to the northwest of the town of Chake-Chake.
The ruins are the remains of Africa's oldest known Muslim town, which may have been founded as early as the eighth century. Early writers mention the town and Matambwe Island, which lies to the north, as the two major trading centres of Pemba. Both these sites have been carbon dated, with results indicating that they were in use in the ninth and tenth centuries. The town seems to have declined for reasons not yet known around the sixteenth century.
The ruins mainly date from the thirteenth and fourteenth centuries, though there are indications that they were built over older foundations. Notable among these ruins are those of a large mosque which was for some time the largest structure of its type in sub-Saharan Africa.