The Belgian railway line 37 is a railway line in Belgium connecting Liège to Aachen in Germany.

Completed in 1843, the line runs 47.4 km in Belgium.

It is the first and oldest cross-border railway line worldwide.

Since 2009, high speed trains running between Brussels and Aachen use the HSL 3 instead of the line 37 between Chênée and Hergenrath.

This European rail transport related article is a stub.