Prabalgad Fort in its present form, was built during Bahmani Sultanate to keep an eye on Panvel Fort and Kalyan Fort in North Konkan. Around 1458 AD, Malik Ahmad, the prime minister of the kingdom of Ahmednagar, took over the fort during his conquest of Konkan. After disintegration of Bahmani Sultanate, this fort remained with the Ahmadnagar Sultanate. During the collapse of the Ahmadnagar Sultanate, Shahaji tried helping them unsuccessfully against the separate forces of the Mughal Empire and the Adil Shahi dynasty and moved to Muranjan, along with wife Jijabai and younger son Shivaji for a brief period. However following Shahaji’s defeat and agreement of Mahuli, North Konkan, along with this fort, was ceded to Mughals who granted ruling authority of the area to Adilshah of Bijapur. The fort was conquered by Shivaji from the Mughals in 1657, after he establishing himself in the Kalyan-Bhivandi area. At the time of the attack the fort was governed by Kesar Singh, a Mughal sardar, and was the only fort to put up a strong resistance. On seeing the signs of defeat the women in the fort performed Jauhar, a tradition of self-immolation to ensure an honorable and respectful death. Singh died during the battle in October 1657. Singh’s mother hid herself and her grandchild during the attack. Shivaji in an act of kindness made sure the lady and the child were allowed a safe passage out.
In the year 1826 Umaji Naik, a freedom fighter, and his associates are believed to have made this as their home for a brief period of time. https://en.wikipedia.org/wiki/Prabalgad
Prabalgad Fort is located between Matheran and Panvel, at an elevation of 2300 feet in the Western Ghats. It was built on a plateau very close to Matheran, but unlike Matheran it does not have a good source of water. It was known as Muranjan until it was taken over and renamed by the Maratha forces under Chhatrapati Shivaji’s rule. The fort contains a temple to Ganesh and some stone ruins. Its sister fort is Irshalgad.
Prabalgad is also known as Muranjan fort currently. Prabalgad was built to keep the watch on the Panvel fort and the Kalyan fort in the north side of the Konkan by the Bahmani Sultanate. In 1458 AD during the capture of Konkan region Malik Ahmed, the prime minister of Ahmednagar kingdom.
After the fall of Bahmani sultanates the fort stayed with the Ahmednagar sultanate. During the end of the Ahmednagar Sultanate, Shahaji Raje moved to Muranjan with his wife Jijabai and son Shivaji Maharaj for long time, after unsuccessfully helping them against the powerful forces that were Mughal Empire and the Adilshahi family.Shahaji Raje followed defeat and the agreement of Mahuli, Mughals surrendered this fort with the north Konkan and Prabalgad. Mughals gave authority of Prabalgad to Adilshah of Bijapur.
In 1657 Chhatrapati Shivaji Maharaj captured Prabalgad from the Mughals during the establishment of Kalyan – Bhivandi area. During the attack of Chhatrapati Shivaji Maharaj, Kesarsingh a Mughal sardar was the governor of the fort he was the only Mughal sardar who gave a strong challenge to Chhatrapati Shivaji Maharaj.