The Tolson Museum sits in Ravensknowle Park, a Victorian pleasure ground on the eastern edge of town, in a handsome Italianate mansion that was gifted to the borough in 1919. The collection covers Huddersfield's history from prehistoric times through its centuries as the engine of the British worsted and woollen trade — the tools, looms, and pattern books of the textile industry are particularly well represented, and give real substance to the mills you see from the train and the hillsides.
The archaeology galleries include Roman finds from the fort at Slack, and the natural history section has the bones-and-cases feel of a proper Victorian regional museum. None of it is flash, which is precisely the point: this is a place that trusts its collection rather than its curation, and it's better for it. Entry is free.
Ravensknowle Park itself is pleasant — a formal garden with a duck pond and enough mature trees to make it worth a stroll before or after the museum. Combined with a walk to Castle Hill, it makes for a half-day of the town's best free attractions.