The Kalka - Shimla railway was one of the best I've ever been on. It was clearly a triumph of British pride and industrial-revolution engineering skills, imperial money and a lot of cheap labour. The entire line is composed of bridges, tunnels and curves, winding the railway through and up the forested hillside to the summer seat of government during the Raj era.
Shimla itself was a lovely place, after having spent a lot of time in busy cities. In the centre they ban both cars and smoking, as well as littering and spitting - all of which make it a refreshingly clean and relaxing place to walk about in.