Book excerpt: The art of mosaics is of ancient origin, enjoying its first great period during the Roman Empire and its second in eighteenth and nineteenth century Rome, when a flourishing craft developed in response to the Grand Tour. Affluent tourists provided the ideal market for views of Rome and images from Ancient History and mythology, painstakingly worked in tesserae - minute pieces of coloured enamel - a technique known as 'micromosaics.' Some of these were so intricate that one square inch could contain as many as 1,500 tesserae. The range of objects was enormous - from jewellery and snuffboxes to large pictures and tabletops. All of these forms and subjects are comprehensively represented in the Gilbert Collection. This book examine the collection through full-colour illustrations and detailed descriptions and commentaries. New research into the workshops and business practices of two significant Roman mosaicists derived from the archives of the Vatican Mosaic Workshops is detailed in an essay by Massimo Alfieri, while Judy Rudoe explores the techniques and materials of small-scale Roman micromosaic objects, illustrated with spectacular magnified photography.