Rani Ka Talab is a small historic tank in Ambala Cantonment, ringed by temple activity and local evening walkers. It is the kind of place that makes more sense at sunset than at noon: families, devotional visits, and a pocket of water in a city otherwise defined by roads and rails.
The site is modest, but useful if you are staying near the cantonment or waiting for a train. Pair it with Holy Redeemer Church or the European Cemetery and you get a good feel for Ambala Cantt's mixed civic, military, and religious landscape.