Jantar Mantar is an important landmark of Delhi and a unique edifice. It is an observatory built by Sawai Jai Singh II, the erstwhile ruler of the princely state of Amber and a contemporary of the Mughal emperor Aurangzeb. Constructed in 1724, this structure lies at the heart of the city as a symbol of the technological strides of the Rajput dynasty.  The various abstract structures within the Jantar Mantar are, in fact, instruments that were used for keeping track of celestial bodies. Nevertheless, the Jantar Mantar is not only a timekeeper of celestial bodies: it also tells a lot about the technological achievements under the Rajput kings and their endeavor to unravel the mysteries pertaining to astronomy.

Constructed in the year 1724, the observatory was the result of Sawai Jai Singh’s passion for astronomy related subjects. It was called the Yantra Mantra. Jai Singh built four other such observatories in Jaipur, Ujjain, Mathura and Varanasi.Jantar Mantar was created to monitor movements of the celestial bodies. It consists of different abstract structures which were used to know the deepest secrets of the universe.
During the reign of Muhammad Shah, the Hindu and Muslim astrologers were involved in brainstorming debate about certain planetary positions. So to put an end to that and also to determine the most auspicious hour for the emperor’s expedition, Sawai Jai Singh decided to rectify the astronomical tables. This resulted in the construction of Jantar Mantar.

A massive masonry observatory, Jantar Mantar is a collection of massive stone astronomical instruments that aid in making accurate astronomical calculations. Raja Sawai Jai Singh drew inspiration for the construction of Jantar Mantar from the observatory at Samarkhand that was constructed by Ulugh Beg. Several astronomical experiments were carried out at the massive Jantar Mantar that were utilized for creating astronomical tables that were later compiled Zij Muhhamad Shahi. The four main instruments at Jantar Mantar are the Samrat Yantra, Jayaprakash Yantra, Misra Yantra and the Ram Yantra.
An integral part of India's scientific and historical heritage, the Jantar Mantar in Delhi is a history seekers delight. The term Jantar Mantar owes its origin to the Sanskrit terms 'Yantra Mantra' that mean instruments and formulae.
The two concave hemispheres at the Jayaprakash Yantra are simply marvelous. Used to note the local time, Sun's position and zodiac signs, the Jayaprakash Yantra was especially significant. The Ram Yantra was utilized to determine celestial co-ordinates and the Misra Yantra was used to find out the shortest and longest days of the year.

Air:-Delhi has an international Airport, the Indira Gandhi International Airport. Taxi and Coach Transfer, pre paid taxis, air conditioned and non A/C coaches all can take you to the Jantar Mantar from the Airport.

Rail:-Delhi is also the hub of Indian railways Network with trains running to and from all parts of the country.

October to March