Try and visit one of the underground city tours while you’re there: https://www.beneath-the-streets.com/ http://www.undergroundtour.com/
The first link is the newer tour company, which I haven’t tried myself, but I hear it’s the better experience.
Either way, it’s worth doing it at least once!
Yes there is: https://addons.mozilla.org/en-US/firefox/addon/clearurls/