Forts of Shivaji figure many in number. He constructed a chain of three hundred or more forts, covering a length of over a thousand kilometers, running along the Western Ghats mountain range. Each of the many forts were placed under three officers of equal status lest a single traitor be bribed or tempted to deliver it to the enemy. The officers, who were called Sabnis, Havladar, Sarnobhat, acted on a joint basis and provided mutual checks and balances. At the time of his death, Shivaji had control over three hundred and sixty forts.

All of the forts have been rather remarkably constructed. Certain outstanding features can be detected in almost all of the fortifications. The most remarkable feature is the adaptable pattern of its designs. There is no monotony seen in the construction of these forts. The designs of the forts correspond to the topography and are in harmony with the contour. Unlike in the case of most other forts of the time, there is seen the absence of ornate palaces, dance floors, gardens and temple complexes in these forts of Shivaji. Most of these forts have a double line of fortifications such as Pratagad fort, Rajgad etc and there can be seen a remarkable foresight in the selection of the sites of the fort. There is not much difference in the area of the higher or lower ranks and there existed a system of inspection of forts by higher ups including the king. Other features of these forts include marvellous acoustics in the capital, community participation in the defense of forts, three tier administrations of forts and the sanskritisation of fort names. Many of the forts, such as the Panhala Fort and Rajgad existed before Shivaji but others like Sindhudurg and Pratapgad were built by him from scratch. These forts have been central to his empire and they remain one of the foremost sources that provide information about his rule. The technical know-how and knowledge of Shivaji is amply evident in the construction of the Gingee fort in Chennai.

Some of the hill forts which were spread over long distances were supported by sea forts. For instance, the hill fort of Salher in Nashik district was at a distance of twelve hunred kilometers from the hill fort of Gingee. The sea fort of Kolaba, near Mumbai was at a distance of five hundred kilometers from the sea fort of Sindhudurg. All of these forts were put under the control of a havaldar with a strong garrison, and rather strict discipline was maintained. These forts were of much use during the Mughal Maratha wars.