Of the five observatories built by Sawai Jai Singh II, Jaipur is the largest one and also the best preserved. It was built between 1728 and 1734. I found a huge collection of 16 instruments, which is often described as "the most logical and realistic landscape stone". Some of the tools are still used to calculate the temperatures that will be reached in summer, the arrival date, duration and intensity of the monsoon and the possibility of floods and famines. A special highlight is the Samrat Yantra, a sundial of 23 meters high, which is expectated to forecast the annual harvest. It is here where I have experienced the most heat of any of my travels.