Although it is not possible to visit all the Heritage Sites of India in a single tour, what you can do is visit a lot of Heritage Sites if you have planned a vacation in India for more than 30 days or so.
Let’s say you have planned a trip to India which will last for almost a month. In that case, some of the most important Heritage Sites in India which you can choose to visit are, the Taj Mahal & Fatehpur Sikri in Agra, Jaisalmer Fort, Kumbhalgarh Fort & Ranthambore Fort in Rajasthan (as part of Ranthambore Wildlife Safari), Khajuraho Temples in Madhya Pradesh, Ajanta & Ellora Caves in Maharashtra, Hampi ruins in Karnataka, a few churches in Goa, take a ride in the Nilgiri Mountain Railway in Tamil Nadu & Sunderbans in West Bengal.