a fragment of the world's largest ancient sundial samrat yantra

landmark architecture tourism monument town ruins fragment largest ancient sundial samrat yantra world's blue sky background walls sandstone staircase marble surface curved measuring scale visible jantar mantar sun dial yantra sky sandstone staircase marble surface curve scale measurement great wandering unesco brihat observatories sightseeing astrology sundial attraction tourists stairs clock steps unique jantar astronomical instrument india observatory jaipur observation astronomy science time wall historic monument famous historical heritage city history old ancient stone travel