Built in 1725 by Maharaja Jai Singh II of Jaipur, Jantar Mantar is a huge sun-dial known as the Prince of Dials. It was also used to observe the movements of stars and planets. The instruments at Jantar Mantar are fascinating for their novel approach. However, it has now become impossible to predict the time accurately because of the towering buildings that surround it. Recently the area has been restored to it's pristine glory.