Going to the hills is one of the preferred ways for Indians to escape the heat in the plains. The British rulers had the same needs and constructed some spectacular train tracks in the 19th and at the beginning of the 20th century. Some of them are still up and running until today.
The short trains are for sure no TGVs, but the scenic rides with countless bridges and tunnels are well worth while. You may sit jammed in historic compartments on wooden benches like in the Nilgiri Hills and some of the rides will test your patience like the one from Kalka to Shimla lasting up to five hours.
However, for fans of historic trains, these rides are a must. You will never get a better chance to enjoy the green sceneries of the Indian hill stations and experience the slow pace of 19th century traveling.