Zaria is spread out and the distances between the old city, the university campus, and the modern commercial district are too far to walk comfortably in the heat. Motorcycle taxis (okadas) are the fastest and cheapest way to move around; agree on the fare before you ride. Shared minibuses (danfos) follow fixed routes and are very cheap but can be slow. Yellow taxis operate throughout the city and are a sensible choice for longer trips or if you are carrying luggage.
The old walled city itself is best explored on foot — the lanes are narrow and the best things to see are off any road accessible to vehicles. Hire a local guide at the entrance to the old city if you want to go beyond the main sights; they know the workshops and family compounds that are otherwise invisible to visitors.