Warkworth Castle - 10' squares turn out to be more historically accurate than we all thought

From the very earliest days of D&D people have criticized dungeons and castles that conform to 10' x 10' squares: that it's unrealistic that any castle or dungeon would be built to conform to a grid. Indeed my extensive visits to many Medieval Castles in the UK seemed to confirm that they were all anything-but designed to a grid.

Last summer whilst on holiday in Northumberland we visited Warkworth Castle, a fantastic medieval castle dating from the 1200s. It is fairly ruinous, but the late 14th century "Great Tower" only fell into disrepair in the 17th century and was restored less than 200 years later so is in remarkably good condition.

Warkworth Castle

At first glance Warkworth Castle appears to be as irregular any other castle, and there is certainly no regularity in the layout of the curtain walls.

As always I purchased a guidebook, as since childhood I have collected maps of all the castles we visit. Many of these maps are disappointing affairs, often very small and lacking detail such as the different floors. The Warkworth guidebook has a reasonable foldout map at the back (and a larger "pretty" isometric map inside which clarifies how the stairs connect) - but what attracted my attention was a note and a diagram in the margins that shows that Warkworth Castle was drawn to a grid, just not a 10' x 10' one, and not at all for the reasons you'd expect...

Here is the margin note, and the diagram in question:

So, for financial reasons, the Keep of Warkworth Castle is laid out on a grid - it just happens to be a 8' 3'' grid, not a 10' one. I looked online for any references to this fact and could not find any, anywhere. Always being sceptical of accepting something purely because it was printed in a book (for example, Ian Flemming did not get 007 from a secret signature of John Dee, Astrologic and Scientific advisor to Queen Elizabeth I - despite this "fact" being printed in books and widely repeated), I decided that in this case it was at least reasonably easy to verify - I just had to overlay a grid on the plan.

The first stage is to align the maps of each of the levels as layers in an image that superimpose on each other. Then I added a grid to match the illustration in the book to the first floor. Then we can see how the same grid looks for the ground and the second floor. Here are the plans for the three layers of the keep with a grid superimposed:

I think you can see from the central map I've managed to get it to line up to the grid as per the guidebook diagram, and also that the other levels are all aligned the same.

So how well do all the levels conform to the grid?

Many rooms clearly conform to the grid - such as The Great Hall (5x3), the Solar (5x2), and the northern Wine Cellar (2x2). But some of the walls are so thick they disturb the pattern - for example, the southern Wine Cellar is only 4x1.5 because the south wall is half a square thick.

In trying to make sense of the wall thicknesses, first we see that the outer walls on the ground floor are almost exactly one square thick (but sometimes containing stairs) and on the inner facing side they contain small rooms. The other walls on the ground floor are half a square thick, except those supporting thicker walls on higher levels (the kitchen).

The Fireplaces in the 2-storey high kitchen, which are shown
as alcoves on the lower level, and thick walls on the upper.

On the upper floors the walls are half a square for the external walls, and thinner internally - except (1) where there is a stair in the east wall of the Great Hall, and (2) the chimneys in the north and east sides of the 2-storey high kitchen (see photo on the left). Walls are above where there were walls on the lower floors (since they are heavy and made of stone, not like a modern house with partition walls).

One final oddity to note is that although the keep is drawn to a 13x13 grid, with the central square being a shaft (a light well), the octagonal towers on each side of the Greek Cross are not regular - the north and west ones are central, but the south and east ones are strangely offset by exactly half a square. I'm unsure of whether this was done for external architectural reasons or for the layout of the interior rooms.

Clearly the keep does conform to the grid, and now armed with some better understanding of the different wall widths I'm in a position to redraw the keep as an accurate D&D map, strictly conforming to a grid. The map needs to show stairs clearly, so that you can understand what joins to what; it needs to mark architectural features such as fireplaces and windows clearly; it needs to make the two-storey rooms and the central three-storey light well clearer. Armed with the many photos I took on my visit I should be able to interpret the plan correctly and draw a clear accurate map for a future blogpost.