Users with more than 25,000 reputation score have access to site analytics. This includes the ability to see how many views the most viewed posts have had in the last 30 days, last 14 days, last 7 days, last two days, or today.
An example of what is currently the most viewed posts in the last 30 days:
The reason why My Girlfriend is going to prison...Save her with Math got so many votes is because it appeared under "hot network questions" and has a clickbait title. People not just from this site, but from all Stack Exchange sites, were clicking on the title when they saw it in their sidebar, just to see what it was about.