rafa_font, 
What happened when staff forgot to lock Gothenburg Library on a day-off?
SPOILER: nothing special.
"400 people visited the facility throughout the day and 245 books were checked out through the automatic counter system"
"The entire day ended up being an unwitting experiment for the possibility of operating an entirely automated library without staff"
From TheMayor.EU:
https://www.themayor.eu/en/a/view/what-happened-when-staff-forgot-to-lock-gothenburg-library-on-a-day-off-12186