The Museo Interactivo de Historia de Lugo gives the city a contemporary history museum to sit alongside its famous Roman walls. Its galleries use models, images, and multimedia displays to explain how Lugo grew from a Roman settlement into the Galician city you walk through today.
It is most useful early in a visit, before tracing the walls or wandering the old centre. The museum is not the reason to come to Lugo, but it gives helpful context and makes the archaeology and street plan feel less abstract.