original_query: What is the significance of the Boat Shed (Number 78) at Sheerness Naval Dockyards?
query: What is the significance of the Boat Shed (Number 78) at Sheerness Naval Dockyards?
answer: The Boat Shed (Number 78) at Sheerness Naval Dockyards, built 1856-60, is significant as the earliest large metal-framed building still standing.  It's a pioneer in the development of metal frames, though not entirely of cast iron, it is constructed entirely of cast and wrought iron members.