Why it looks like this

The city began as a company town for the MIBA diamond concession in Belgian times, when access was tightly controlled. After independence, people came anyway: Mbuji-Mayi became the capital of the Luba heartland and one of DR Congo's largest cities, growing over the diamond-bearing ground itself.

Most of that growth was informal — streets made by use rather than by plan — and artisanal diggings surround and even pierce the urban area, making a map where mining and city are the same thing.