Coordinates: 18°32′46″N 72°55′38″E / 18.5461°N 72.9272°E / 18.5461; 72.9272 Chaul is a former city of Portuguese India, now in ruins. It is located 60 km south of Mumbai, in Raigad District of Maharashtra state in western India.

In 1508, the Egyptian Mamluks, allied with the Gujarat Sultanate vanquished the Portuguese in the Battle of Chaul. The first Portuguese settlement at Chaul took place in 1521 with the construction of the first fort on the south bank of the Kundalika River. In October 1531, the Portuguese erected a new square stone fortress, named Santa Maria do Castello, which contained a church and dwellings for 120 men. A town developed around the fortress, but a 1558 treaty precluded fortifying the town. The town was destroyed in a 1570-71 siege by the Nizam Shahi Sultan of Ahmadnagar, but a treaty was concluded which lifted the siege, and the town was rebuilt and surrounded by walls and bastions. A fort (Korlai fort) was built on the Morro de Chaul, a rocky promontory on the north side of the river opposite the town. The town withstood several further attacks, and its defense works were expanded in 1613.