abaneri
on the way from gurgaon to sikandra (village on the jaipur-agra highway) you come across some lesser known monuments of rajasthan like abaneri or chand baori as it is known locally. built sometime around the 8th-9th century by raja chand of the chahmana dynasty. it is 19.8m deep and is fed by ground water even to this day, although the water's pretty murky now.
found it amazing even at 46 deg C!