Ratnadurg Fort, Ratnagiri
This fort was built during the Bahamani rule. In 1670, Shivaji conquered the fort from Bijapur ruler Adil Shah. In 1790, one Dhondu Bhaskar Pratinidhi rebuilt the fort, and strengthened its ramparts. The fort has the shape of a horseshoe, with a length of 1,300 meters and a width of 1,000 meters. The Arabian Sea surrounds it on its three sides. One of the fort's bastions, "Siddha Buruj", has a lighthouse which was built many years ago in 1867 and rebuilt to its present form in 1962. A temple of Goddess Bhagwati is located inside the fort. Wikipedia