How to get referral (inner) link

Hi there, here's my problem. I have the whole site pages that might point in anymoment to a map page where customer choose the country he belongs to. I need to save the url they where before to enter into the map page. something link "request.request_uri" but that works for the previous page.. I thought I'd need something that acts like history.back(); with javascript but I need to store that param in session..

how can I do that?! thanks :wink: Andrea