Routes problems

Hello.
I have many links like these:
/articles/...
/albums/...
/photos/...
etc.

I need to use the name of the city in the beginning of urls if the
user has choosed it:
/city_name/articles/...
/city_name/albums/...
/city_name/photos/...

But previous links shoul work too (/articles/..., /albums/...)