 It was constructed in the 18th century by the Venad kings of Travancore, Later it was modified under the supervision of Captain Eustachius De Lannoy, an ex-Dutch naval officer of the Dutch East India Company, who became commander of the Travancore Army (the very army that defeated him in the Battle of Colachel) in the 18th century, after he earned the trust of the Travancore King Marthanda Varma.De Lannoy reconstructed Vattakottai, as part of the defence-fortifications he undertook throughout Travancore.The fort is made of granite blocks and, today, a part of the fort extends into the sea.