The Ujjain Observatory, located in the city of Ujjain, Madhya Pradesh, is believed to be the oldest astronomical observatory in the world, dating back to the 5th century BCE.

Varahamihira, a renowned Indian astronomer and mathematician, is credited with establishing the Ujjain Observatory in the 6th century CE.

The Ujjain Observatory was primarily used for observing and predicting celestial events such as eclipses, solstices, and equinoxes.

Jantar Mantar, located in Jaipur, Rajasthan, is famous for its Samrat Yantra, a large sundial that was used to measure time and track the movement of the Sun.

Sawai Jai Singh II, the Maharaja of Jaipur, commissioned the construction of five Jantar Mantar observatories in the 18th century.

The Jantar Mantar observatories were primarily used for observing the Sun and planets, and for measuring their positions and movements.

The Man Mandir Observatory, located in Varanasi, Uttar Pradesh, was built in the 16th century and is known for its unique architectural design.

Raja Man Singh, a Rajput king and a renowned astronomer, is credited with establishing the Man Mandir Observatory in the 16th century.

The Man Mandir Observatory was primarily used for studying the stars and constellations, and for observing their movements and positions.

The Jantar Mantar observatory in Delhi is one of the five observatories built by Sawai Jai Singh II in the 18th century.

The Jantar Mantar observatory in Delhi is significant for being the largest of the five Jantar Mantar observatories, containing the largest sundial in the world, and being used to observe the transit of Venus in 1761.

The Vedhshala Observatory, located in Mathura, Uttar Pradesh, is an ancient observatory that was built in the 16th century.

Raja Birbal, a renowned courtier and astronomer in the court of Emperor Akbar, is credited with establishing the Vedhshala Observatory in the 16th century.

The Vedhshala Observatory was primarily used for observing the Sun and planets, and for measuring their positions and movements.

There is no ancient Indian observatory located in the city of Kanchipuram.