illumination of charters, and occasional survivals like the fifteenth century Doom painting at Guthrie. Surviving copies of individual portraits are relatively crude, but more impressive are the works or artists commissioned from the continent, particularly the Netherlands, including Hugo van Der Goes's altarpiece for the Trinity College Church in Edinburgh and the Hours of James IV of Scotland. Architecture Medieval vernacular architecture utilised local building materials, including cruck constructed houses, turf walls and clay, with a heavy reliance on stone. As burghs developed there were more sophisticated houses for the nobles, burgesses and other inhabitants. By the end of the period some were stone built with slate roofs or tiles. Medieval parish church architecture was typically simpler than in England, with many churches remaining simple oblongs, without transepts and aisles, and often without towers. From the eleventh century there were influences from English and continental European designs and grander ecclesiastical buildings were built in the Romanesque style, as can be seen at Dunfermline Abbey and Elgin Cathedral, and later the Gothic style as at Glasgow Cathedral and in the rebuilding of Melrose Abbey. From the early fifteenth century the introduction of Renaissance styles included the selective return of Romanesque forms, as in the nave of Dunkeld Cathedral and in the chapel of Bishop Elphinstone's Kings College, Aberdeen (1500–09). Many of the motte and bailey castles introduced into Scotland with feudalism in the twelfth century and the castles "enceinte", with a high embattled curtain wall that replaced those still in occupation, were slighted during the Wars of Independence. In the late Middle Ages new castles were built, some on a grander scale as "livery and maintenance" castles, to house retained troops. Gunpowder weaponry fundamentally altered the nature of castle architecture, with existing castles being adapted to allow the use of gunpowder weapons by the incorporation of "keyhole" gun ports, platforms to mount guns and walls being adapted to resist bombardment. Ravenscraig, Kirkcaldy, begun about 1460, is probably the first castle in the British Isles to be built as an artillery fort, incorporating "D-shape" bastions that would better resist cannon fire and on which artillery could be mounted. The largest number of late medieval fortifications in Scotland built by nobles were of the tower house design. primarily aimed to provide protection against smaller raiding parties, rather than a major siege. Extensive building and rebuilding of royal palaces in the Renaissance style probably