Construction of strongholds in OD&D, or any version of D&D for that matter, has always been quite a vague subject with just a few rules scattered around the rulebooks which mostly seem to have been ignored. Here are some quick insights I have noted to help shed some light on to the subject...

Underworld & Wilderness Adventures explains that it’s “mandatory to hire an Engineer to build any major stronghold.” and an engineer costs 750 gold pieces per month, but the book gives no indication whatsoever of how long it takes to build any structure! The AD&D Dungeon Masters Guide helps. It says on page 106 “Fortress-like stone constructions take about one week per 10’ cubic section. Normal stone buildings as shown on the cost list, require four months to construct, including interior work.”

Construction of strongholds in OD&D

The prices of construction are incredibly confusing! There are a few discrepancies that I searched high and low to clarify. Namely, the illustration that lists the prices says “gate house & gate (3,000), then there is a side view drawing of a gatehouse which says 9,000 and also a top down view of a gatehouse which says 4,500. I was almost beating my head against the wall trying to deconstruct all this but I finally had an epiphany...

If we presume that the 3,000 is actually the price of the gate itself and not the gatehouse. i.e. the actual stone portal that is built into the structure (bear with me on this), and we presume a basic gatehouse is 4,500 then we might also say that the 9,000 gold piece gatehouse costs more because it has battlements on its roof, 2 barbettes, which you can just make out! A draw bridge and portcullis and several arrow slits.

You can actually make out more details by looking at the illustrations in an earlier edition of the book. On this you can actually see the portcullis and count the arrow slits, of which there are 12, perhaps the 6 in the later illustration implies 6 on each side!

I was actually able to experiment to see if I was on the right track. I broke down the 9,000 gold illustration of the gatehouse. Let’s presume we have a basic gatehouse that is 4,500 gold pieces, the barbettes cost an additional 2,000. The arrow slits are a further 120 gold pieces and the portcullis and drawbridge are 2,000. All this added together is 8,760 gold pieces, so we are close to our target of 9,000. If we presume then that the 110’ of battlements on the top cost a further 240 and a double set of stone stairs inside costs a further 140, then we have some extrapolated logic for our 9,000 gp gate house.

Now, this could be wishful thinking but we can experiment further by looking at the cost of the barbican. Similar to the gatehouse the illustration shows a basic top down barbican at a cost of 14,000 and a side view complete with a gate and portcullis, curtain walls on top of the towers and arrow slits. I counted 16 on the early version of the illustration. If we break the barbican into separate parts as we did with the gatehouse, 14,000 for the basic structure, 3,000 for the gate, 160 for the arrow slits, 1556 for the curtain wall (I based this on the size of the one in the illustration and calculated what it would cost for the size required on the barbican). There would need to be a single set of stone stairs in each tower which would cost another 360 and 200’ of battlements (based on the cost of the battlements on the gatehouse) would cost 436 gp. We are now at just over 19.5k of our target of 20k. But we haven’t added the portcullis yet, if a portcullis and drawbridge together cost 2,000 then we can reconcile this by presuming the portcullis costs 500 and the drawbridge 1,500. We then end up with 20,012 gold pieces. 

We are so close to the costs in the illustration with this rationale that I feel this is beyond being a little coincidental and instead more or less indicates we are very much on the right track. By simply rounding down the prices to the nearest 10 we land right on the money with 20,000.

We are in a desirable position now because using this as a starting off point we can extrapolate further to enable us to find prices for all the individual parts that make up the options presented, we can recalculate at different scales and so on and the more we drill down and update costs back and forward between the various elements the more precise the logic becomes.

Were ready now to look at the cost of building a keep. The example given in the book is a round keep with two towers and costs given for each tower. What seems to be presented is a tower with each story having arrow slits every 10’ (according to the earlier illustration) a top story of windows every 10’ and a curtain wall on top. There is also an instruction to increase or decrease the size of the towers by either adding 20% to the cost or deducting 10% of the cost per 10’. I had a mess around with this and the maths is actually off. Add 20% and then subtracting 10% does not produce consistent results. But if we look at this whole thing a different way it makes more sense. In the interests of saving space to keep printing costs down, rather than providing sketches of these towers ranging from 10’ in width to say 200’ this simple formula could have been included instead. So to increase width above 90’ (the width of the larger tower) add 10% per 10’. To decrease width below 50’ (the width of the smaller tower) subtract 10% per 10’. The same thing can be done for the height but adding or subtracting 20% instead. This works consistently if you work from a base size. If you start with the 30,000 gp tower and work forwards or backwards from there, adding 10% per 10’ of width you get consistent results. These results can be plotted on a graph which can then be referred to at any time to calculate the cost of building a keep of any size.

Curiously, the earlier prints of Underworld & Wilderness Adventures (before the final 7th print) has some additional text in the construction section which has prices for building wooden buildings and palisades.