How to preserve the old link structure after migrating to WP

I have a site with the following link structure:
domain.pl/name-of-the-city/point-of-interest.html

The problem is that the last element “point-of-interest.html” is often the same on different cities e.g.:

docelowo.pl/amsterdam/zabytki.html
docelowo.pl/berlin/zabytki.html

Of course the for WP it is impossible(?) to save twice the same last element – it save it like zabytki.html and zabytki-2.html

I really do not want to use redirect 301, because I did it twice before and always lost a lot of audience…

So my question: Is this any way I could preserve the old link structure in WP?
Maybe I could leave slash in permalink like “berlin/zabytki.html” – but I did not find how to do it.
And maybe another twisted way?

Thank you in advance for help.
Dominik