The Cairngorm Mountain Railway is the highest railway in the United Kingdom, climbing from the Coire Cas ski base station to a terminal at 1,085 metres in under ten minutes. It was built partly to replace vehicular access to the upper ski area and partly to give the general public access to the Cairngorm plateau without requiring a strenuous uphill walk. The top station has a cafe and exhibition space.
Note that the railway is run as a commercial ski facility, and in summer there have been restrictions on passengers walking onto the open mountain from the upper terminal — a matter of ongoing controversy between the operating company and hillwalkers. Check the current policy before visiting if you intend to walk to the Cairn Gorm summit from the railway. In winter the operation shifts to ski mode and the railway serves as a ski lift.