This medal was produced to mark the Great Exibition of 1851. According to the Victoria and Albert Museum " the Crystal Palace was a huge glass and iron structure erected in Hyde Park in London to house the Great Exhibition of 1851. The exhibition attracted over six million visitors and numerous firms capitalised on its success by issuing cheap, mass-produced medals as souvenirs. The building required 3300 supporting columns, 2224 principal girders all amounting to 3800 tons of cast and 700 tons of wrought iron; 600,000 cubic feet of timber, 205 miles of glazing bar and 900,000 square feet of glass. The exhibition opened on 1 May 1851. During its 141 days, it was visited by 6,039,195 people with an average daily attendance of 42,831.Approximately 14,000 exhibits, divided into four main categories, and shown by 8200 exhibitors were on display: raw materials, machinery and mechanical inventions, manufactures, sculpture and plastic" See: art.http://collections.vam.ac.uk/item/O111683/the-great-exhibition-crystal-palace-medal-messrs-allen-moore/