Pedestrian tunnel under the Miljoenenlijn along the Eyserbeek

The Schaesberg–Simpelveld railway, also known as the Million Line (Dutch Miljoenenlijn), is a 12.5 km long railway line between Simpelveld and Schaesberg in what is now the municipality of Landgraaf in the province of Limburg in the Netherlands, opened in 1934 and connects the Aachen–Maastricht railway with the Sittard–Herzograth railway line. The name of the only mountain route in the Netherlands derives from the high construction costs, which totaled 12.5 million Dutch guilders, since the hilly landscape required extensive earthworks with deep cuts and high dams. In 1988, the section from Simpelveld to Kerkrade was initially shut down, but was reopened as a museum railway in 1995 after it was taken over by the Zuid-Limburgse Stoomtrein Maatschappij (ZLSM). Regular passenger traffic currently only takes place on the section between Landgraaf and Kerkrade-Centrum, which has been electrified since 1986. This section was operated from 2007 by the company Veolia Transport, which offered continuous trains every half hour from Kerkrade via Heerlen and Valkenburg to the Limburg provincial capital Maastricht. Since 2016, the Arriva company has operated a train connection from Sittard to Kerkrade Centrum every half hour.

Here you walk together with the Eyserbeek under the million line

Special passage under the railway embankment.
Nice and cool on a hot day.
The tunnel is quite long, for some people it may be a stretch
(by the way, sufficiently wide) walkway can be useful.