Hi again, Flavio!  More on the subject of "at" and "in":   
      
             I was glad to see your comment in another echo, BTW, that you don't   
   mind waiting awhile for answers.  WRT complex grammatical issues I tend to be   
   slow to respond because I'm thinking of examples & looking for patterns.  :-)   
      
      
             "I'll meet you at the ABC Restaurant in Richmond" was one example I   
   used earlier.  Another which occurred to me later is from an old song:   
      
                  Meet me in St. Louis, Louis,   
                  Meet me at the fair.   
      
      
             We use "in" with names of cities, towns, or villages.  Usually such   
   places have clearly defined boundaries.  I gather you live in or near Recife,   
   which according to my atlas is within the province or state of Pernambuco.  I   
   see that Brazil is a very large country by comparison with other countries in   
   South America & that Recife is on the east coast.  If you're not sure what to   
   write about but want to improve your English, tell us more about Brazil.  The   
   eyes of the world are on your country because of the Olympic Games.  And as I   
   used to advise my students, "Write about what you know"....  :-)   
      
             We use "in" with names of neighbourhoods (e.g. Greenwich Village in   
   New York City & Notting Hill in London).   
      
             We use "in" with names of states (e.g. Queensland, Kentucky, Idaho)   
   ... with names of shires in Great Britain... with names of counties in (e.g.)   
   Ireland & the USA... and with names of Canadian provinces & territories.   
      
             We use "in" with names of countries.   
      
             We use "in" WRT other physical areas which are more or less clearly   
   defined, such as a house or a garden... and by extension we use "in" if we're   
   referring to (e.g.) a book, a painting, a Fidonet echo, or a "frame of mind".   
      
             We often use "in" WRT a particular month or year... but we also use   
   "at" or "on" WRT to time.  I'll deal with that issue in another chapter.  ;-)   
      
      
      
      
   --- timEd/386 1.10.y2k+   
    * Origin: Wits' End, Vancouver CANADA (1:153/716)