Green Park Station closed to trains in 1966 and was converted, its Victorian wrought-iron and glass roof still intact, into a covered market and event space. The Saturday farmers' market fills the original platform area with local producers: cheese from the Somerset levels, cider, honey, meat, bread, and street food from the surrounding stalls.
The building itself is worth seeing whether or not you buy anything. The light through the old glass roof is excellent on a clear morning. Arrive between 9am and 11am for the full selection, many of the better stalls sell out by midday.