The Jungfraujoch — the saddle between the Mönch and Jungfrau peaks — is reached by a remarkable rack railway that departs from Kleine Scheidegg, itself reached by train from Grindelwald or Wengen. From Grindelwald the journey takes about an hour and a half each way, with a change at Kleine Scheidegg. The train passes through tunnels cut inside the Eiger, with two intermediate stops — Eigerwand and Eismeer — where windows look out through sheer rock faces onto the void.
At the top (3,454 m) there is a platform with views across the 23-kilometre Aletsch Glacier, the longest in the Alps, and into southern Switzerland. The Sphinx Observatory on the ridge offers an even higher vantage point. Snow conditions permitting, you can walk out onto the glacier itself. The round trip from Grindelwald is expensive (around CHF 215 without a rail pass), and the top is often clouded over — check the webcam before setting off. The best months are June to September; winter offers the glacier without crowds but requires warmer clothing.