The Ujjain Observatory, also known as the Vedh Shala, is the oldest astronomical observatory in India. It is believed to have been built in the 5th century BCE by the astronomer Varahamihira.

The Jantar Mantar in Jaipur was built by Sawai Jai Singh II, the ruler of Jaipur, in the early 18th century.

The Jantar Mantar is a collection of astronomical instruments that were used to measure the time of day, track the movement of the stars, and predict eclipses.

The Jantar Mantar does not have a sundial. The other instruments listed are all found at the Jantar Mantar.

The Samrat Yantra is the largest instrument at the Jantar Mantar. It is a sundial that is used to measure the time of day.

The Jai Prakash Yantra is an instrument that is used to track the movement of the stars.

The Rashivalaya Yantra is an instrument that is used to determine the position of the zodiac signs.

The Man Mandir Observatory is located in Varanasi, Uttar Pradesh. It was built in the 16th century by Raja Man Singh.

The main instrument at the Man Mandir Observatory is the Vrihat Samrat Yantra. It is a sundial that is used to measure the time of day.

The Yantra Mahal Observatory is located in Delhi. It was built in the 16th century by Raja Jai Singh II.

The main instrument at the Yantra Mahal Observatory is the Misra Yantra. It is a sundial that is used to measure the time of day.

The Govardhan Hill Observatory is located in Mathura, Uttar Pradesh. It was built in the 16th century by Raja Man Singh.

The main instrument at the Govardhan Hill Observatory is the Digamsha Yantra. It is an instrument that is used to measure the altitude of the sun.

The Charminar Observatory is located in Hyderabad, Telangana. It was built in the 16th century by Muhammad Quli Qutb Shah.

The main instrument at the Charminar Observatory is the Naubat Khana. It is a drum tower that was used to announce the time of day.