The Grange Cavern near Holywell began as a limestone quarry in the nineteenth century, part of the area’s wider industrial use of Halkyn Mountain for stone and lead.

During the Second World War, the Ministry of Defence requisitioned the site, adapting its underground galleries to store up to 11,000 tons of bombs, with local accounts even suggesting that Barnes Wallis’s “bouncing bombs” were held there.

After lying unused for several decades, the quarry was transformed in the late 1970s into the Grange Cavern Military Museum, which displayed tanks, vehicles, medals, and military artefacts within the cavern’s dramatic underground setting. The museum proved popular for a time but eventually declined, and by 1989 it closed.