Since 1912, the Jungfraujoch has been accessible to tourists by the Jungfrau line, a railway from Interlaken and Kleine Scheidegg, running partly underground through a tunnel through the Eiger and Mönch.

It lies east of the saddle, below the Sphinx station, and is connected to the Top of Europe building, which includes several panoramic restaurants, shops, exhibitions, and a post office.

The Swiss- and Austro-Bavarian-German term Joch means "saddle", in this case referring to the ridge between two higher peaks, as recorded in the 14th century (Grimm, Deutsches Wörterbuch "bereits im 14. jahrh.

[4] The south side (canton of Valais), almost flat, is constituted by the Jungfraufirn, one of the branches of the Aletsch Glacier, the longest in the Alps.

The north side (canton of Bern) is almost vertical with a difference of height of nearly 3,000 metres from the bottom of the valley at Interlaken, with no easy natural access.

Nearly all built infrastructure, including the Jungfraujoch railway station, Top of Europe complex and the Sphinx Observatory, are on the Valais side of the border, therefore in the municipality of Fieschertal.

There is a tradition in the Bernese Oberland, supported by some documentary evidence, that a pass existed between Grindelwald and Fiesch in Valais in the late medieval period, later lost to the advancing glaciers.

With the early development of tourism in Switzerland and the exploration of the High Alps in the 19th century, there were once again attempts to traverse the great ridge that encloses the head of the Aletsch Glacier, and connecting Fiesch with Grindelwald and Wengernalp.

Four such routes were found, with the Jungfraujoch and the Eigerjoch being among the most difficult passes in the Alps,[5] despite the former having a relatively easy southern approach on the Aletsch Glacier.

The final and very arduous stage in the ascent was a single patch of dark rocks jutted out from the snow in the ridge connecting the Jungfrau with the Mönch.

When construction finally finished, the railway reached only to the height of the Jungfraujoch saddle, rather than the summit of the Sphinx, and had only two intermediate stations.

However, even in its current state, the Jungfraubahn is a significant achievement in engineering and construction, still holding the title for highest railway in Europe.

The windows have been placed in holes used to remove excavated rock from the tunnel during construction, and are also occasionally used as access points, by climbers, and also rescue parties.