It was in the bathroom, 2cm in lenght (or so). It has two small antenas on the head. I live on Balkan peninsula, inland.
That is a European Millipede.
I found this picture by searching European Millipede. Obviously there are different types - and this is the one you have. Here is a wiki link I found: https://en.wikipedia.org/wiki/Cylindroiulus
I think your specifically is a Cylindroiulus britannicus