Dating back to 1779, from South East corner of this vast quadrangle. More at; Link from which the following extract has been taken
"The Grade I listed Piece Hall, Halifax is a rare and precious thing, an architectural and cultural phenomenon which is absolutely unique. It is the sole survivor of the great eighteenth century northern cloth halls, a class of buildings which embodied the vital and dominant importance of the trade in hand woven textiles to the pre-industrial economy of the West Riding of Yorkshire, from the Middle Ages through to the early nineteenth century.
Dating from 1779, when it was built as a Cloth Hall for the trading of ‘pieces’ of cloth (a 30 yard length of woven woollen fabric produced on a handloom), The Piece Hall was the most ambitious and prestigious of its type and now stands in splendid isolation as the only remaining example. It is one of Britain’s most outstanding Georgian buildings."
SE0925 : Dean Clough, "D Mill" Dean Clough is indeed a wondrous complex. The best view of all is from the North Bridge Flyover. This is barred to pedestrians so don't blame me if your master shot gets you arrested. A half way decent walk round this complex to get pictures is a couple of hours and probably a couple of miles too.