All along the northern section, the W9 route follows a cross-border greenway of 125 km known as the ‘Vennbahn’ or Fen railway line, one of Europe’s longest and most beautiful greenways, which crosses three countries. It is part of the RAVeL network and has been laid out along the path of old railway lines, No 48 from Raeren to Saint-Vith/Sankt-Vith and No 47 from Saint-Vith to Lengeler and the Luxembourg border.