This excellent little museum uses interactive displays, free audio guides, video footage and everyday objects to tell the story of Cardiff’s transformation from a small market town into the world’s biggest coal port and then into the capital city of today. Downstairs is the City Lab, with kids' activities and exhibits on the history of protest in Cardiff.
There's also a left-luggage desk (each piece £5 to £10 per day, collection by 3.30pm the following day).