I visited this place with my friends on a busy sunday morning. The place was fairly crowded and situated in the middle of the city. The entry fees is Rs 20/- for Indian tourist and Rs 150 for Foreigners.
There are many structures made in a park which were used in the ancient times to get exact time as well as other weather information. Every monument has a stone placed nearby on which every detail is placed. The place is not so cool for young crowd, but surely an eye candy for those you want to visit or get more knowledge about ancient times.
The place is very close the the famous Hawa Mahal of Jaipur. I would suggest to everyone to take the visiting pass for all five monuments at once as it will help you save money and time both.