Why not print out the content of the page? Just change the last line of your first example to

print $cityResponse->content;
[download]

and you get the HTML which contains, where you'd expect your information to be, "We're sorry. The page you're trying to access is temporarily unavailable. Please try again later."

This could just be because they don't want you scraping their data, they want you to look at their ads, or it could be something more fiddly to do with JavaScript or cookies. Anyway, your code seems to be working just fine, only their server doesn't like it.

I think you should check out WWW::Mechanize, and you should note that the article you're basing your code on is five years old.