Africa

The African continent has, despite its enormous size, very little subterranean sights. The reasons are diverse:

The geologic situation is not very good for karst and cave development. Most areas of Africa are covered by an old kraton, a very old tectonic unit consisting mainly of crystalline and metamorphic rocks. So there are only small areas of limestone, often metamorphized to marble.
The climatic situation is also not very good for the development of caves. Huge areas are arid, other areas are lowlands covered by swamp and rain forrest.
The history, most countries were in a Stone Age stage of development until the white people arrived. There was little mining activity and little exploration activity. The exploration of the white invaders was focused on exploiting the resources, not on tourism.
The low development of most countries is a reason for the lack of inland tourism and also a lack of foreign tourism, often combined with an instable political situation, making it very unlikely that show caves or show mines are developed.

So, despite some world famous mines and several interesting karst areas, the number of subterranean sights is pretty low. Best developed is South Africa with its numerous archaeological sites. Other states have some caves, often in a very low state of development. Most important are cultural caves which were used as hideouts or to build cave houses.

Additional Information about Africa
South Africa
North Africa GeoNet
The Ten Best Caves to Visit