We arrange the site after public closing with an astronomer rather than a monument guide. The difference is the whole experience: you are shown how to take a reading, why the Samrat Yantra is built at that angle for this latitude, and what the instruments were actually used for at court.

Ninety minutes is the right length, ending as the light goes. There is no crowd, no queue, and no competing guide with a megaphone - which in the middle of Jaipur is not a small thing.

October to March only, when the late light is clear. Permission comes from the state department and is granted a few evenings a week, so we need three weeks and a little flexibility on the exact day.