The Wamala Tombs are one of Kampala's important Buganda heritage sites, traditionally associated with Kabaka Suuna II. They are less famous than the Kasubi Tombs, but that is part of the appeal: the visit is quieter and more focused on local royal memory.
Go respectfully, and expect a cultural site rather than a polished museum. The tombs help make sense of Kampala as the centre of a living kingdom as well as a national capital, especially if you are also visiting the Kabaka's Palace or Kasubi.