The Cinema Museum is an eccentric London collection devoted to cinema-going: posters, projectors, uniforms, signs, stills, and all the small things that made old picture houses feel like an event. The building adds another layer, as it was once a workhouse where Charlie Chaplin lived as a child.
You cannot usually just wander in. Visits are by guided tour, screening, or event, so book ahead and treat it as a planned stop rather than a rainy-day fallback.