Tombs
I think there are two distinct sets of areas to place traps. The first is tombs and graves. Places that hold the dead. The easiest justification for having traps here is religion. The builders believe that at some point in the future the bodies need to be taken away.
This is likely to be combined with some mummification process, either Egyptian or Incan. It might even be bog mummies. Now, why do they need to be taken away? Maybe a savior will come that lets all the dead rise and join him on a journey. The savior will be smart enough to solve the puzzle and mere mortal plunderers will be blocked.
Alternatively, maybe the puzzles aren't really puzzles, but a mere test for the spirits/souls of the dead. They would see through them with ease. Again, it's us mortals that need to stay out, while still allowing the spirit to reclaim his body at the right time.
Cities
This is harder to justify. Entrances to settlements can be guarded with fake or hidden paths against outsiders visiting. I'm not sure those or a maze would count as a puzzle.
Again, religion can be used. Maybe their religion foretells a great end of the world that starts with all of the chosen people dying. But maybe the buildings are shielded against spirits. Lined with salt, herbs or runes, to keep the evil spirits in the dark outside.
But now the souls of our chosen ones are trapped inside. Maybe they need guides, valkyries, to take them to the afterlife. Perhaps the intricate locks are made for such divine creatures. Simple mortals and ghosts struggle but, divine beings can easily open them.
A completely different approach: maybe they weren't build as puzzles. Their society build a very extensive network of pullies and levers. Opening doors, trapdoors for supplies, adjusting machinery. Now over time things broke. Instead of a well working system it became a broken death trap.
Perhaps the system doesn't rely on inorganic cogs and ropes. Maybe it's organic and without caretakers it grew, made connections it shouldn't. Maybe the switch for the door now also open the airlock. A broken one that's now filled with poisonous gas instead of the supposed medical herbs. Again a death trap.
43Why else would eccentric millionaires fill dungeons with gold? – PyRulez – 2016-02-20T02:59:05.060
43From pokemon to skyrim this is a terrifying question... – wposeyjr – 2016-02-20T03:05:06.720
46It may have been a prison, not a fortress. You actually came from the easy side. – Kolaru – 2016-02-20T15:19:56.740
70Lab rats must wonder that as they go through the maze to get the cheese. Maybe you are a lab rat trying to get the gold. – Bellerophon – 2016-02-20T18:27:36.410
4@Kolaru The other direction started with a level that opened all the gates, because the developers wanted to ensure that, if a player somehow found their way from the other side, they wouldn't be trapped. – Frostfyre – 2016-02-20T18:42:49.380
4@Frostfyre: that's an after-market mod they made when they stopped using it as a prison? Darn legacy door system. – Steve Jessop – 2016-02-21T02:20:59.383
5Try Robert Sheckley's "Hands Off" short story. Two parties exchange ships on an uninhabited planet. From humans' perspective, the alien ship is filled with traps. From alien perspective, human ship lacks basic life-support facilities, so they have to engineer some crude replacements. – Dallaylaen – 2016-02-21T12:36:12.983
3Key point - it was a Dwemer ruin. The Dwemer disappeared millenia ago under mysterious circumstances and nobody really knows anything about them other than the ruins they left behind. Who knows why the heck they did anything? – Darrel Hoffman – 2016-02-21T19:55:25.807
41
In a fantasy setting with mindless creatures (undead, constructs, simple AI), such 'puzzles' exclude mindless creatures while being easy for intelligent creatures to pass. This is one fan theory about Skyrim's claw puzzles, keyed combination locks with the combination written on the key, rendering the combination portion entirely superfluous to anything intelligent enough to match up the symbols.
– Jeffrey Bosboom – 2016-02-21T21:55:50.030See: "Harry Potter and the Chamber of Secrets"
– WBT – 2016-02-21T23:09:30.7338@JeffreyBosboom Wow. A Turing test against zombie! – Dallaylaen – 2016-02-22T00:42:20.407
@JeffreyBosboom - That's not just a fan theory, I think that was explicitly stated at some point in the game. – Darrel Hoffman – 2016-02-22T19:10:51.097
1https://xkcd.com/370/ panel 3 is relevant :) – Jacob Krall – 2016-02-23T15:51:21.810
1For deterring adventures, archaeologists and tomb raiders who are trying to take their cultural artifacts ;) – Carlos Danger – 2016-02-23T15:55:03.317
It's all for science
– Wayne Werner – 2016-02-23T20:37:56.7331
"This kind of system can't be used for defense" - this conclusion cannot go without a reference to The Bard's Tale.
– O. R. Mapper – 2016-02-23T21:29:33.7002Read the Mistborn series by Brandon Sanderson. The climax of The Bands of Mourning takes place in such a dungeon, and it's so out of place in an otherwise realistic world (modulo the fantasy elements of course) that even the characters remark on how weird and pointless it is. Then one of them figures out the reason why, and it all makes sense... and then at the very end of the book you find out the rest of the reason why, and it will totally blow your mind. Not going to say what actually happened because it involves massive spoilers for the entire series, but... yeah. You should read it. – Mason Wheeler – 2016-02-25T15:15:00.243
@JeffreyBosboom However, one thing that makes the symbols extremely obscure and unintelligible is the fact the claws are nowhere near the locks they open. In order for anyone to ever discover how the symbols relate to the claw in any way, the person must already possess the claw (no small feat there) and have found and fought all the way to the locking mechanism. The odds of someone carrying the claw with them to that exact location deep within obscure crypts is extremely unlikely and hence a reasonable level of security. This assumes when the claws & locks were made, they were secret. – Thom Blair III – 2016-10-31T20:46:58.043
If it was in real life, I wouldn't want to even try messing up with levers in an obscure dungeon without quicksave ... – Ise – 2017-01-18T15:06:37.743
One of the beautiful aspects of Riven, the vast majority of the puzzles were very natural and fit perfectly into the environment. first step was usually trying to figure out that there was a puzzle there to begin with – Innovine – 2017-01-23T07:27:38.703