Lying in the heart of the Delhi's commercial center near Cannaught place is the uniquely raised structure…Jantar Mantar, which means the 'instrument of calculation'. Built by Maharaja Jai Singh of Jaipur to keep track on celestial bodies and solve mysteries regarding astronomy, it's the most happening place in Delhi. Jantar Mantar is opened daily from sunrise to sunset for all with no entry fee. This awe-inspiring building is a must see for every Delhi tourist.