DGA3939614: Siege tower, woodcut from De re militari libri quatuor (Epitoma rei militaris), by Publius Flavius Vegetius Renatus, printed by Christian Wechel, Paris, 1535 / Bridgeman Images

DGA3938581: Quick-firing rotating bombard platform, siege engine, woodcut from De re military, by Roberto Valturio, printed by Christian Wechel, Paris, 1532 / Bridgeman Images

DGA3938943: Shape of protective covers (H), shape of ditch shelter (I), and frames for protective covers (K, L), copperplate engraving from Diffesa et offesa delle piazze, by Pietro Paolo Floriani, published by Giuliano Carboni, Macerata, 1630 / Bridgeman Images

DGA3938190: Special iron columns, United States of America, engraving from Nouvelles annales de la construction, 1870 / Bridgeman Images

NWI4914008: Reproduction of a drawing by Leonard de Vinci (Leonardo da Vinci, 1452-1519) for a device for digging a canal / Bridgeman Images

DGA3954035: Fort of Sao Joao da Foz, at mouth of Douro River, Porto, Portugal, illustration from Teatro universale, Raccolta enciclopedica e scenografica, No 353, April 10, 1841 / Bridgeman Images

KES6205312: Switzerland Art Leonardo Da Vinci, 1971 (b/w photo) / Bridgeman Images

LLM5213752: Leonardo da Vinci Monument, Milan (b/w photo), European Photographer, (19th century) / Bridgeman Images

CUB4527222: Statue of Leonardo da Vinci, Uffizi, Florence, Tuscany, Italy / Bridgeman Images

DGA3683485: Leonardo da Vinci Institute and library, Empoli, Tuscany, Italy / Bridgeman Images

KES6205319: Switzerland Eth Zurich Leonardo Da Vinci, 1954 (b/w photo) / Bridgeman Images

DGA1586428: Young motherhood, 1991, Bertocci, Carlo (b.1946) / Bridgeman Images

KES6205316: Switzerland Eth Zurich Leonardo Da Vinci, 1954 (b/w photo) / Bridgeman Images

DGA3939655: Siege ladder, woodcut from De re militari libri quatuor (Epitoma rei militaris), by Publius Flavius Vegetius Renatus, printed by Christian Wechel, Paris, 1535 / Bridgeman Images

DGA3938552: Siege platform, woodcut from De re military, by Roberto Valturio, printed by Christian Wechel, Paris, 1532 / Bridgeman Images

DGA3939927: Producing silver discs immediately after fusion, engraving from De Re Metallica (On Nature of Metals), by Georg Agricola, published in Basel in 1561 / Bridgeman Images

DGA3939635: Woodcut from De re militari libri quatuor (Epitoma rei militaris), by Publius Flavius Vegetius Renatus, printed by Christian Wechel, Paris, 1535 / Bridgeman Images

DGA3939617: Siege engine, woodcut from De re militari libri quatuor (Epitoma rei militaris), by Publius Flavius Vegetius Renatus, printed by Christian Wechel, Paris, 1535 / Bridgeman Images

DGA3939368: Embossed silver medallion with Medusa's head / Bridgeman Images

DGA3938564: Siege ladder and climbing shoes, woodcut from De re military, by Roberto Valturio, printed by Christian Wechel, Paris, 1532 / Bridgeman Images

DGA3938565: Rope and wooden siege ladders, woodcut from De re military, by Roberto Valturio, printed by Christian Wechel, Paris, 1532 / Bridgeman Images

DGA3938704: Water pump, copperplate engraving from Theatrum Machinarum Novum, Plate 71, by Georg Andreas Boeckler, Coloniae Agrippinae (Cologne), 1662 / Bridgeman Images

DGA3938774: Water-raising machine, copperplate engraving from Theatrum Machinarum Novum, Plate 148, by Georg Andreas Boeckler, Coloniae Agrippinae (Cologne), 1662 / Bridgeman Images

DGA3939924: Refining silver, preparing containers, engraving from De Re Metallica (On Nature of Metals), by Georg Agricola, published in Basel in 1561 / Bridgeman Images

DGA3938553: Spears transport frame, woodcut from De re military, by Roberto Valturio, printed by Christian Wechel, Paris, 1532 / Bridgeman Images

LAL319840: Leonardo da Vinci painting his masterpiece 'The Virgin on the Rocks', McBride, Angus (1931-2007) / Bridgeman Images

DGA3938531: Bolts, woodcut from De re military, by Roberto Valturio, printed by Christian Wechel, Paris, 1532 / Bridgeman Images

DGA3938542: Device to enter window protected by grille; lifting device, woodcut from De re military, by Roberto Valturio, printed by Christian Wechel, Paris, 1532 / Bridgeman Images

DGA3938560: Scythed siege engine, woodcut from De re military, by Roberto Valturio, printed by Christian Wechel, Paris, 1532 / Bridgeman Images

DGA3939761: Mine shaft, engraving from De Re Metallica (On the Nature of Metals), by Georg Agricola, published in Basel in 1561 / Bridgeman Images

DGA3939767: Wagons for transporting earth and minerals from a mine, engraving from De Re Metallica (On the Nature of Metals), by Georg Agricola, published in Basel in 1561 / Bridgeman Images

DGA3939364: Hercules and lion, embossed silver-plated plaque / Bridgeman Images

DGA3939409: Saint Ambrose, polychrome majolica tile / Bridgeman Images

DGA3938174: System for removing combustion by-products from kitchen ovens (Mousseron system), engraving from Nouvelles annales de la construction, 1865 / Bridgeman Images

DGA3939906: Closed furnaces for mercury fusion, engraving from De Re Metallica (On Nature of Metals), by Georg Agricola, published in Basel in 1561 / Bridgeman Images

DGA3939929: Letter D, drop cap, engraving from De Re Metallica (On Nature of Metals), by Georg Agricola, published in Basel in 1561 / Bridgeman Images