Probably to make sure the customers know that they mean it. There are often a lot of people coming in one minute before closing time that don’t leave in time.

I think they did that in castles, because it’s generally pretty hard to build castles. If the enemy is inside the walls you are practically done anyway.

Sounds like an urban legend. Who do you mean anyway? James Couzens? Harry Bennett? Charles Sorensen? His son Edsel? They all died of natural causes.