Which among following Indian railway routes was considered as "Crown Jewel" during British time and also includes the world's highest multi-arch gallery bridge ?

The correct answer is The Kalka-Shimla Railway.

Key Points

• Kalka Shimla Hill Railways is one of the most iconic railway routes in India.
• This railway line started in 1903 and it holds the Guinness Book of World Records for offering steepest rise in altitude in the space of 96 kilometres. 
• It is a popular tourist attraction.
• The 96 km long narrow gauge track passes through about 102 tunnels, 900 curves, 800 bridges and viaducts.
• Due to its scenic beauty it is also known as the 'crown jewel' of the Indian Railways.
• The maximum height of the track on this route is 2000 m above the sea level.
• It is also a World Heritage site of UNESCO.