Jantar Mantar is an astronomical observatory to explore a scientific thesis in red stone. Situated near Connaught Place, it was raised in 1710 in Delhi by Raja Jai Singh II of Jaipur (1699-1743). This observatory features mason-built astronomical instruments to map the positions of different planets, sun and the moon. Raja Jai Singh had a keen interest in astronomy and astrology and thus, established four other such observatories at Ujjain, Jaipur, Varanasi and Mathura (Jantar Mantar in Mathura no longer exists today).
The word “Jantar Mantar” was formed collectively with the Sanskrit words: 'Yantra' and 'Mantra', the basic elements to make the observatory work. The yantras or the instruments, namely samrat yantra, jai prakash, ram yantra and niyati chakra- used in the observatory were built of brick rubble and plastered with lime. These were the basic elements used to make various astronomical calculations.
Even though these instruments are unable to make accurate observations today, due to tall buildings around the observatory, the building of Jantar Mantar is an integral part of India's scientific heritage. It is one of the major technological achievements under the rule of the Rajput kings. Set amidst lush green lawns, the place is frequently visited by people to spend romantic evenings or to see the grand scientific construction. The best part about the Jantar Mantar is the Misra Yantra or Mixed Instrument, near the main entrance. Even today, this instrument is capable of depicting the time of four other places in the world accurately when it is noon in Delhi.