Castles look as if they have always been there, rising out of crags and riverbanks as though they grew from the rock. Each of them was in fact a major building project. Someone designed it and paid for it, quarrymen cut the stone, and carts and boats moved it to the site, often in difficult terrain and under the threat of attack. Thanks to surviving royal accounts and a remarkable modern experiment in France, we know a good deal about how this work was done.
From Earth and Timber to Stone
The first castles in England and much of northern Europe were not stone fortresses at all. After the Norman Conquest of 1066, William the Conqueror’s followers threw up hundreds of motte-and-bailey castles: an earth mound (the motte) topped by a timber tower, with a fenced enclosure (the bailey) beside it. Forced local labor could raise one in a matter of weeks. They were cheap and quick, and they let a small occupying force control a large territory.
Over the following generations, the most important sites were rebuilt in stone. Stone resisted fire and rot, and it made a statement of permanent power. The White Tower in London, begun in the 1070s, is one of the earliest great stone keeps. By the thirteenth century, castle design had grown far more sophisticated, with multiple rings of walls, projecting towers that let defenders shoot along the walls, and heavily fortified gatehouses.
The Master Mason
Medieval castles had no architect in the modern sense, but each major project was led by a master mason. He combined the roles of designer, engineer and site manager. The best-documented example is Master James of St George, a mason from Savoy, in what is now the border region of France and Italy. King Edward I of England brought him to Wales after the conquest of 1277–1283. James is closely associated with the great castles of North Wales, including Harlech, Conwy and Beaumaris. Historians still debate how much of each design was personally his. At Caernarfon, for instance, another master, Walter of Hereford, played a major role, and some scholars credit him with much of the design.
Master masons worked out the plan on site, often scratching designs onto plaster tracing floors or using templates for repeated shapes such as window tracery and arrow loops. They supervised cutting, setting and the overall geometry, and they were among the best-paid people on the payroll.
An Army of Workers
Edward I’s Welsh castles are unusually well documented because the royal government kept detailed accounts. They show building on an industrial scale. Workers were recruited from across England, sometimes by compulsion. Sheriffs were ordered to send quotas of diggers, carpenters and masons to North Wales.
A famous letter written in 1296 by James of St George and a colleague, reporting on progress at Beaumaris Castle on Anglesey, gives a sense of the scale. During the previous season, they wrote, the work had needed about 400 masons, both cutters and layers, together with 2,000 less skilled workmen, 100 carts, 60 wagons and 30 boats bringing stone and sea coal. Wages were badly in arrears, and the builders warned that the workforce could not be held together without money.
The workforce was organized by skill. Freemasons carved fine freestone for windows, doors and decorative work. Rough masons and layers built the main walls. Quarrymen extracted stone, often from sites nearby or across the water, while carpenters built scaffolding, cranes, roofs and floors. Smiths made and resharpened tools constantly, since iron chisels and picks blunted quickly against stone. Lime burners produced mortar. Plumbers, despite the name, worked lead for roofs and gutters. Many more unskilled laborers dug ditches, carried loads and mixed mortar. Women and children often appear in building records doing carrying and other unskilled work.
The Cost
All this was hugely expensive. Records suggest that between 1277 and 1304, Edward I spent around £80,000 on his castle-building program in Wales, and around £95,000 by 1329. At a time when a laborer might earn a couple of pence a day, these sums represented a large share of royal income. Caernarfon Castle and its town walls alone cost somewhere between £20,000 and £25,000 between 1284 and 1330.
Money troubles often shaped the result. When a Welsh rebellion broke out in 1294, Caernarfon’s unfinished walls were overrun and work had to be redone. Beaumaris, begun in 1295 and often described as the most perfectly symmetrical of the Welsh castles, was never finished. Building stopped around 1330 with its towers still short of their intended height, because the crown’s attention and money had moved to wars in Scotland and France.
Tools and Techniques
How did builders lift tons of stone without engines? The main answer was human muscle and simple machines. Small loads went up ladders and ramps on workers’ backs or in hods. Heavier blocks were raised by windlasses and by treadwheel cranes, large wooden wheels in which one or two people walked to wind a rope around an axle. Scaffolding was built of timber poles lashed together, and its horizontal members were often set into small holes in the wall. These “putlog holes” can still be seen in many castle walls today, sometimes running in neat diagonal lines that trace the path of spiral ramps used during construction.
Walls were usually not solid stone all the way through. Builders typically laid two faces of dressed or roughly squared stone and filled the space between with rubble and lime mortar. Lime mortar sets slowly. Building could pause in winter, when frost might damage freshly laid work, and unfinished walls were often covered with straw or thatch to protect them.
Guédelon: Building a Castle Today
Much of what we know about the practical side of this work comes from an unusual experiment. In 1997, at a former quarry in a forest in Burgundy, France, a team led by Michel Guyot began building a new castle, Guédelon, using only techniques and materials available in the thirteenth century. Stone, wood, sand, clay, lime and iron ore all come from the area. Workers quarry stone by hand, forge tools, make mortar and lift blocks with treadwheel cranes.
The project has become a major experimental archaeology site and tourist attraction, drawing hundreds of thousands of visitors a year. It has tested how fast masons can work, how many people a treadwheel needs, and how scaffolding and mortar behave in practice. Its findings have even fed into conservation work elsewhere, including discussions around restoring traditional craftsmanship at Notre-Dame de Paris after the 2019 fire. Guédelon has been under construction for nearly three decades, partly because it is run for education rather than speed, but also because it shows how much labor a castle really required.
Built to Impress as Much as to Defend
Castles were military buildings, but they were also residences, administrative centers and political statements. Caernarfon’s banded masonry and polygonal towers are often thought to echo the walls of Constantinople, possibly to link Edward’s rule to imperial Roman authority. Fine halls, chapels and private chambers were built alongside the defenses. A castle needed to be strong, and it also needed to look powerful to anyone who saw it.
Standing in a ruined castle today, it is easy to imagine knights and sieges. The building accounts point to a different story as well. Every wall stands because thousands of named and unnamed workers cut, carried and set stone, and because a government decided it was worth paying for them.
Sources
- Cadw: Beaumaris Castle
- World History Encyclopedia: Harlech Castle
- NPR: In France, workers build a castle from scratch the 13th-century way
- Review of Malcolm Hislop, James of St George and the Castles of the Welsh Wars
Featured image: Benoît Prieur / Wikimedia Commons, CC0
