Jaigarh Fort  

One of the few ancient Indian military structures to be kept intact through the ages, Jaigarh Fort has recently been opened to the public. It was sealed for seven years, due to a rumour, that an enormous treasure in gold was buried, in the fort area. The fort houses several palaces, gardens, a granary, an armoury, temples, and most significantly the Jai Ban, the largest antique canon, in the country. 

It is within walking distance of Amber, and offers a fantastic panaromic view of the surrounding plains, from the Diwa Burj watchtower. 

For detailed information, see Jaipur.

Some of the forts and palaces you could visit while touring India are
Agra Fort, Agra
Gwalior Fort, Gwalior 
Fatehpur Sikri, Agra  
City Palace, Jaipur 
Jaigarh Fort, Jaipur
Hawa Mahal, Jaipur
Amber Fort, Jaipur
Nahargarh Fort, Jaipur 
Mysore Palace, Mysore
Red Fort, Delhi
Golconda Fort, Hyderabad