The small railway heritage display associated with Mettupalayam station introduces a much larger living monument: the Nilgiri Mountain Railway. The line climbs from roughly 326 metres at Mettupalayam to about 2,203 metres at Udhagamandalam, or Ooty, across 45.88 kilometres of metre-gauge track. UNESCO added it to the Mountain Railways of India World Heritage property in 2005 because its engineering and continued operation document the challenge of connecting mountain communities.
Proposals for a railway into the Nilgiris appeared in 1854, work began in 1891, and the complete route was operating by 1908. The difficult lower climb required a rack-and-pinion system: a toothed rail between the running rails engages the locomotive mechanism to manage gradients beyond those of an ordinary adhesion railway. Seeing equipment, photographs and station infrastructure at Mettupalayam makes that principle easier to understand before the train enters the hills.