Huddersfield town centre is walkable — the station, the art gallery, the market, and the main shopping streets are all within ten minutes on foot. Castle Hill is about three miles south of the centre; a taxi or bus will get you to the base, with a short walk to the top.
For the wider area, a car is useful but not essential. Buses run from the bus station on Upperhead Row to most local villages and valley towns, including Marsden (for the Standedge Tunnel) and Holmfirth (the Holme Valley). The rail network connects Huddersfield to Dewsbury, Wakefield, Sheffield, and Leeds on frequent services. Cycling is feasible on the valley roads but the Pennine terrain is unforgiving; the canal towpaths offer flatter riding and take you away from traffic.