Thank you so much for your answer.
Maybe you do not get my question, maybe I am missing something.
I made a drop down menu with 10 cities. Boston, NY, etc. http://www.example.com/tag/boston, http://www.example.com/tag/NY. Every articles is filtered and shows up only thus post related to it city, like Boston or NY.
But if I go to any other menu they are not related to this city. For example.
I have one menu as I described above with some cities and some others links. And I have another menu with the mains links like: Nightlife, Restaurants, Travel, etc. If I link over Boston I see only the post related to Boston, but if in that page I make click again over the main links, then it shows up the everything related to this category, but does not filter the active tag or city. And this is what I do not know how to hack.
Thanks you so much for be there reading what I post and help.