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Comment by djrogers | Hacker News Reader

> It's not like we are running low on examples of 1000+ years buildings (https://en.wikipedia.org/wiki/11th_century_in_architecture). These castles, cathedrals, farms, were built to last, so it's appropriate to use them as examples.

This is an easy place to run in to a survivorship bias problem - pick a random 1000 year old farmhouse. How many farmhouses built exactly the same way didn't last for various reasons? Is the fact that one is still standing due to luck, or was it destined to last 1000 years the day it was built?

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If you look at that list, almost all of the surviving buildings are churches or religious places. If the goal is to build something that lasts 1000 years, then you need to factor in political and utility questions as well besides fixating on materials.

Your home can have perfect architecture, but if a rich person buys your land after you are gone and decides what you've had sucks, it will just get demolished and replaced with something more modern. That rarely happens with churches.

> That rarely happens with churches.

I agree. If the church didn't survive, they would just build a new one.

I imagine there lie the remains of hundreds of separate cathedrals under one. But you would never say "the church fell down". Rather, "there was an accident and renovations were required".

I see them as a Ship of Theseus, where the most long-lasting examples were determined through a lot of trial and error.

Isn't this a thing with Notre Dame? It's been a while but I remember the opening of Hunchback mentions the rebuilding right?

Many cathedrals have been rebuilt two or three times, and building a bigger church over the top of a smaller one is normal, but there are also plenty that have survived more or less as they are for at least several centuries. (Hell, there's an 11th century church in my home village, and it still has the door on the wrong side because the village itself was moved due to plague).

Straight masonry without rebar lasts essentially forever - think of all those Roman viaducts that are still in use. Water can wear through it eventually if the shape lets it, especially in places with freeze-thaw cycles (so there's a saying that a church will survive as long as there's someone around to clear the gutters). I guess hurricanes would probably do it if you're in a place that gets those. But there's just not a whole lot to go wrong with what's essentially a big lump of stone. (Of course a bare stone building is not particularly comfortable for living in, and you have to be a bit more careful about how you maintain wood or fabric on the inside - but the building shell itself will last as it is)

Ding ding ding. You can make a canvas tent last 1000 years if you have a maintenance team constantly making repairs. This is 100% an issue with human incentives, not construction technology.

It’s not clear how many of the no longer extant old homes and farms fell down due to design issues, due to neglect, or were pulled down for economic or aesthetic reasons. Most architectural styles go through a process where they stop being made, start getting neglected, most of them get pulled down, and the few remaining ones get lovingly restored as they get old and rare enough to become retro rather than just outdated. This tells us very little about how well they were built, even with survivorship bias in mind, because very few buildings will survive an utter lack of maintenance, and less still if many were torn down for not being stylish enough to command the level of rent that the owner is hoping for.

It doesn't matter that the others fell, we now know what definitely didn't fall - which is all we need to get to.

It matters if you want 99% of the buildings that you build last 1000 years, rather than 0.001%.

Survivorship bias says to look at all the buildings that failed and why they failed rather than looking at the building that survived. You might imitate build but you will not imitate the environment that allowed this one to survive.

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