So, in my campaign the party may be building a domain on the ruins of an old class one market. Now, the place has been ruins for a couple of centuries but surely building from that point would be better than starting from scratch.
How should I handle this?
From D@W there’s the concept of buying raw materials to speed construction time - D@W:Campaigns pg 51, Construction Materials.
In that section there’s a part of scavenging from nearby buildings: If scavenged from nearby buildings, the labor cost is reduced by 25%, but the value of the buildings is reduced by twice that amount. (where the amount being referred to is the cost of the construction project.
So, the guesswork in that may be deciding what the total original urban investment of the settlement was, then decrease that by whatever the decay rate over time of the buildings should be, and then you’re left with the amount of usable material can be drug out of the ruins.
Using the example from D@W:C, if we’re building a 200,000GP stronghold near the ruins, we want to get 50,000 gp worth (25%) of raw materials out of the ruins, max.
A Class I city usually has 20,000 or more families in it. Depending on how you read the Urban Investment Table on pg 133 of ACKS, that minimially-sized Class I may have 2.5 million GP invested in it (to get above the 19,999 family limit, and press it into a Class I)
That 50K we were looking for is 100K of actual materials value (as the value of materials regained is half value taken out of the building) which is only 4% of that investment. I’d expect you’d be able to find at least that much if not much, much more over just a few centuries. Have to do some Googling around, I don’t know if there’s much about the decay rate of real-world sites - that’s the key to deciding the remaining value of a stronghold or settlement over time.
Another thought, since we’d hate to give players anything for free, the value of the raw materials they get out of the ruins should be offset by monster lairs and encounters they occasionally dig up/disturb - the XP value of which could be equal to around a quarter (or less, to be generous) of the value of the raw materials they’re getting out of it.
In this case, that could be a 12,500XP value of monsters - a single venerable dragon, just about.
Randomly, that may give us proof in mechanics of the “dug too greedily and too deep” trope, or the Dwarf Fortress rule - the Moria dwarves got the value of their mining back in a single balrog lair.
I don’t have a good recommendation for going from a fortified city to a stronghold, but the rules do cover stronghold decay.
Let’s assume the stronghold they’re building on top of was one meant to protect the domain in which the class I market was. This would be civilized land, so it would have been a stronghold powerful enough to cover 16 civilized hexes @ 15kgp per hex or 240,000gp (ACKs core p127). This stronghold will require an upkeep of 0.5% of its total cost or 1200gp per month.
I can’t find the rules, which I thought were in domains @ war but may be somewhere in the forums, but this can generally be interpreted as the decay rate of the stronghold. Of course, the cost would taper off after each decay because 0.5% of the total cost would be lower each time. generally, the value of the stronghold after a period of time would be 240,000gp * 0.995^m where m is the number of months the upkeep has not been paid. If we assume 2 centuries, 200 years, 2400 months, then the stronghold should have decayed down to about 1.4gp… so maybe not super valuable. Of course, you could declare that in your world the decay rate is much smaller than 0.5%, or you could come up with a different model. I may also be remembering the rule wrong and it may not lose the whole 0.5% when it goes unpaid.
I found the threat about skimping on upkeep:
http://www.autarch.co/forums/ask-autarchs/skimping-upkeep
it seems the loss is 1200gp every month, so using this model may not produce anything more meaningful that settling in otherwise “empty” hexes.
Good find, Jard.
Yea, there’s a mechanics disconnect between “effective value” for holding a domain, enduring siege, or habitating a garrison, and value as a pile of loose stone or what-have-you.
There should be a way to turn that upkeep deterioration into something though…
I think some sort of a minimum decay value is probably appropriate. I thought this was already a rule, in fact, but I couldn’t find it.
Off the top of my head, I would suggest that wooden structures can decay to nothingness, while stone structures cannot decay below 25% of their original value due to lack of upkeep.
The ratio of wood to stone in urban investment will depend on your setting and the specific town, but I would guess approximately 90% wood/10% stone as a baseline, which would leave a class 1 market with 62,500 gp worth of usable stone left; scavenging this would reduce the labor cost of building your new stronghold by 31,250 gp, to a maximum of 25% of its value.
I also like the idea of monsters having laired in the ruins, using the value as a guide; in this case, about 7812 XP worth of monsters.
Well, they won’t be getting anything for free… the place overlooks a giant haunted necropolis, and under that is Barrowmaze… 
But I figured the stone, the roads, and all of that should be worth something.
Ha. Craig T Nelson approved.
It wouldn’t make sense to have the value dwindle down to nothing. After all, it’s very common for local towns to build their houses from the stones of ancient ruins. (Which could transfer any curse that’s upon the ruin to the town, but that’s another thread)
Big lumps of stone will always have a value. However, after a certain point, ruins will not be habitable at all - and the 25% value point seems to be a nice enough limit for that. You could also rule that underground structures last much longer, slowly turning into populated dungeons. Perhaps we can hack the wizard sanctum/dungeon rules for that.
But another thing crossed my mind. Building on top of an ancient market has other benefits. That market was there for a good reason - it was central, at the mouth of a river, or at a crossroads of trade routes. Perhaps the intrinsic value of such a place is that once investments are made, the trade will begin to flow again faster than normal?