Since its full operation in 1908, the Nilgiri Mountain Railways has been running through the Nilgiri Hills of Tamil Nadu on unique rack and pinion traction to negotiate steep gradient for the 45.88-kilometre long meter-gauge single-track. This mountain railway of India exhibits an important cultural and technological transfer for its construction during 1891 to 1908 and has enabled significant and enduring human settlement, which is continuing till date. In 2005, UNESCO has included it as one of the 30 cultural heritages for its profound influence on social and economic developments of this multi-cultural high mountain region with the exceptional and universal value of a technological ensemble and human civilization.