Everything you've always wanted to know about how a castle was defended--in a fusion of the organic and the technical that David Macaulay hasn't quite achieved before. "On a high limestone outcrop" along the Welsh coast, master engineer James and his staff build a castle and a town for Lord Kevin--to help secure northwest Wales, in 1283, for Edward I. Thus, from one or another bird's-eye view, one sees the site as a ditch outlines the town, a moat cuts off the castle rock, bounding walls and towers rise, houses line the streets and stretch, with their garden plots, to the town wall--where at last, in 1295, Welsh soldiers mount an attack. Meanwhile, one has also watched, close-up, the intricate construction of battlements, towers, gatehouses (and garderobes) designed to make the imaginary "Aberwyvern" an impregnable fortress. So there is no little drama in seeing the attack repulsed, the defenses hold; but Macaulay does it artfully, with pictures (a catapult assembled, and then abandoned), and moves on in good historic order to the town spreading beyond the walls, Welsh and English passing freely through the gates. At the very last "Master James's mighty castle" is a moonlit ruin--ending in romance what began as a calculated plan. The factually-minded and fantasizers will find equal reward here.