In fantasy there are many tropes that are probably wrong and I would like some sources on what was real.

Things like

• roadside taverns; afaik a myth
• dealing with crime
• literacy levels
• underground structures
• leather armor

For taverns, I heard that villages are naturally placed apart, iirc about 4 hours walking. (US has longer distances because technological improvements). What was the reality around travel, trade and food?

And for town guards I heard they only existed in larger settlements. How would smaller villages handle security and crime?

How many people knew how to read and write? And at what level? What did they use it for and if they could not read/write well, how did they send/read messages? Was writing mainly used for accounting and science/history?

Perhaps this is just a fantasy thing, but how did we get to the point where dungeons are typically underground mazes? Building underground is always going to be more difficult than building above ground level, or rather ground water level. If people did build underground, was it mainly as a way to store food because we did not have refrigerators back then?

I always thought leather wasn't used as armor as it was very expensive to make versus fabric, but at some point we switched from the gambeson to "buff coats". Why was this? At least that's for European history ofc. For other regions they did use leather as I assume the quality or supply of iron ore was not enough to produce weapons of such a grade that required similar high grade armor.

These are the subjects I can think of rn, but if anyone has other subjects I'm eager to hear about them :)

TLDR; What (Medieval) Fantasy tropes are true/false and how does it relate to our own world's history?