The 602 metres tunnel of the narrow-gauge railway between Jawornik Polski and Szklary is the longest such object in Europe. It was built in 1903-1904 on the route of the Przeworsk-Dynów Local Narrow-gauge Railway. It is constructed from stone ashlar and was closed by wooden gates to protect against freezing moisture on the tracks, which would create a danger for freight and passenger trains. At its deepest point, it is 37 metres underground, with a width of 4,3 metres and a height of 4,7 metres. Interestingly, the tunnel was not necessary on this route – the watershed could have been overcome by a serpentine route, but the Austrian military authorities opposed this, wanting to have the possibility of easily and durably blocking the railway route in case of war with Russia. This is evidenced by the preserved mining niches.