Himachal Pradesh due to its popularity among tourists can be termed as the crown jewel of Indian tourism industry. It is famous for its adventure sports such as rock climbing, mountain biking, paragliding, ice-skating, trekking and rafting. The development of the hill stations is linked to the colonial past of India, one of the hill stations being Shimla which was The Summer Capital of India during the British raj. Shimla, the state capital, is popular among tourists. The Kalka-Shimla Railway is a mountain railway which is a UNESCO World Heritage Site. The Kalka Shimla narrow gauge Railway was built during the British rule in India with an aim to connect by Shimla the summer capital of British Indian rail network. This rail network holds the Guinness Book of World Records for its 96 kilometers steepest rise in the altitude with crossover of 800 bridges and viaducts, it is one of the most beautiful hill railways in India. It was considered the “crown jewel” of the Indian National Railways during the British Raj. On 8 July 2008, UNESCO added the Kalka–Shimla railway to the mountain railways of India World Heritage Site.