Murud-Janjira Fort

Initially, the Fort was built by the Sultans. However, later one, several additions and changes were made in the architecture by the Marathas. This fortification will offer you a glance into the century-old Maratha history, thanks to the wars' cannons. These tombs have been built as an homage to the fallen, and other artwork spread across the castle. The Fort's entrance is known as the "Sher Darwaza" because of a sculpture with one tiger with six elephants.
Location: 55 kilometers from Alibaug in the Raigad district of Maharashtra.
Sindhudurg Fort

The Sindhudurg fort has many enigmatic tales, like the three water reservoirs, which never dry during the summers. This underground water passage opens to a village at the other end, the hidden entrance gate, or the Dilli Darwaja, and so on. The finesse of the Fort has left many tourists gobsmacked, with wide, open mouths in shock. Shivaji hired three hundred architects from Portugal to construct a fortification that would be their main operational center during any war. So, visiting this Fort is a must.
Location: Along the shore of Malvan town in Sindhudurg district, 450 km south of Mumbai
Vijaydurg Fort

Laterite stones were mainly used in the construction of this Fort. There is a vast guard wall surrounding the Fort, and standing at a distance of 200km from the main building. This wall acted as the first line of defense for the Maratha naval force. Apart from this, you will also see the marks and dents left by the cannonballs on the outer wall.
Location: Situated right at the mouth of the Waghotan River, in the Vijaydurg region of Devgad Taluka
Kolaba Durg

You can wander at the vast sea with no endpoint from the rooftop of the Fort. Some cannons once used to be included in wars. Several carvings of birds and animals are there on the fort walls. There is also a freshwater well sitting at the center of the courtyard and a Lord Ganesha temple.
Location: 2 kilometers away from Alibaug Coast
Suvarnadurg Fort

The Fort's foundation is mainly built from the rocky surface of the island itself. However, some sections are there where large stone blocks have been used. There are two entrances- the 'Maha Darwaja' or the bigger entrance opens towards the land while the 'chor darwaja'; or the smaller one is sea facing. If you want to unearth the history of this Fort, visiting it is a must.
Location: On a small island in the Arabian Sea near Harnai of the Konkan region
Andheri Fort
The Fort has several things to offer to you, starting from the cannons to the iron sculptures which once adorned the walls and hallways of the Fort. Since no jetty is there near the Fort, you will have to visit it during a low tide. The lack of water will help you to walk on foot to reach the structure.
Location: near Mumbai's harbor's mouth, in the south direction from Prong's Lighthouse.