They are a form of forts which were an effective defensive structures and were built in many countries during 19th century. The ones in Mauritius are as well preserved as anywhere else. The thick walls of the forts are generally made of solid masonry which were meant to protect the fort against canon fires, though the introduction of rifled artillery rendered them useless. From inside, the fort is divided into three floors and a basement. Officer's and men's quarters are situated on the first floor whereas ammunition and supply rooms are situated on the ground floor. The canons are mounted on the roof of the fort. These forts are considered an important part of history of Mauritius.