Back in 1728, the Rajah of Jaipur, Sawai Jai Signh II, dispatched his emissaries all over the world to gather data on astronomical predictions and bring it back to him. He wanted to know what the best way was to learn all about the stars. When they came back, he ordered the consecution of the Jantar Mantar complex, which is an astronomical observatory made of stone and influenced by a French mathematician. In total, the Rajah built 5 of these in India, with the largest in Jaipur, containing a 73-foot tall sundial, which is still the largest ever built.
Having actually visited this observatory, I can tell you, it’s pretty fucking impressive and accurate for something built over 300 years ago.