The Museo de la Revolución occupies a former government building on the central park and tells the story of Nicaragua's Sandinista revolution with the directness of people who were there. The guides — many of them veterans — show you confiscated weapons, explain guerrilla tactics, and point to photographs of combatants they knew personally.
The tone is unambiguously partisan, which is part of what makes it interesting. This is not a balanced academic account but a living memory of resistance against the Somoza dictatorship. Even if you know the history, hearing it from someone who fought it is a different experience altogether. The museum is small but densely packed and takes about an hour with a guide.