It might be a blot on the Peak District National Park, but 2,000 people were keen to see inside it on its 85th birthday.
Hope Works, operated by Hope Construction Materials, is the largest cement manufacturing operation in the UK, producing 1.5m tonnes a year.
Visitors were shown the quarry and works and travelled on a steam train which connects it with the mainline.
Bosses also laid on stilt walkers, face painting, donkey rides, a historical exhibition and music.
Industrial director, Ashley Bryan says: “We weren’t lucky with the weather but the event was a big success and we are delighted that so many people came along to help celebrate our milestone.”