The Darjeeling Himalayan Railway (DHR) in north eastern India has been inscribed on UNESCO's list of World Heritages sites. Probably the world's best-known narrow-gauge mountain railway, the DHR was built in 1879.
The line was constructed to reduce the travel time between Calcutta and the hill station of Darjeeling. Until then, Darjeeling could only be reached by bullock or mule cart.
Popularly known as "the Toy Train", the DHR was the first railway on the sub-continent built exclusively with Indian capital.
Rising about 6,850 ft over 50 miles, it has been described as one of the great engineering masterpieces of the 19th century.