Subcategories in portfolio items

Hello,
Great theme.
I am trying to make pages using portfolio items (no prob so far) but want to create large number of pages for sitemap that filters results by category and subcategory OR better still 2 categories.
To be clear let’s consider a simple directory concept with Dentists, Lawyers and Florists. Let’s have 3 locations also: London, Paris, Athens.
I want to display in array of pages, portfolio items for each iteration so:
Dentists in London, Dentists in Paris, Dentists in Athens; Lawyers x 3 etc
So we need to display NOT: Dentists OR London but portfolio items where selected filters BOTH apply => London AND Dentist.

Also is there any way I can generate all these pages in array without manually doing? I appreciate this last task is probably beyond scope of template but perhaps you can point me in right direction.

Many thanks
S