The Museu Nacional de Geologia is one of those small, slightly creaky museums that reward a visit out of all proportion to their size. It occupies a 1930s pavilion just south of the cathedral and holds the country's reference collection of minerals, fossils and rocks — much of it gathered during the colonial geological surveys of the 1940s and 1950s.
The star object is a 3D wooden relief map of Mozambique that fills a whole room — every river, mountain and bay carved at vast scale by hand for the geological service. It is one of the more unexpected sights in the city. The staff are usually keen to walk visitors through the exhibits; entry is free or near-free.