The history of Panerai began in 1860, when Giovanni Panerai opened his watchmaking shop at the Firenze Phone alle Grazie. The brand would move to Piazza San Giovanni somewhat later - the current Firenze Panerai Boutique is still located there. Although a specialist at watches, the Panerai firm would grow fame as a supplier of military instruments, including torches, compasses, depth meters and others. In 1916 the first patent was filed for 'Radiomir', a luminescent substance that would increase the readability of dials of instruments and devices in dim light. In 1936 the first prototype of a Radiomir-type dive watch was shown. Its oversized (47mm) case was fitted with wire-loop lugs and it featured a hand-wound movement. It was produced in cooperation with Rolex.