Ojukwu's Bunker is the underground command post associated with Chukwuemeka Odumegwu Ojukwu and the Biafran government during the civil war. It was built quickly after Enugu fell, when Umuahia became the wartime centre of Biafra.
The bunker is small, stark, and more meaningful with context than as an object by itself. Visit it with the National War Museum if you want the city to make sense.