This once-mighty fort is now home to administrative offices, and though large sections of the structure are crumbling it's still an evocative sight. It was built by the Portuguese in 1628, but the Dutch took over after just 10 years, followed by the Brits. Access is controlled, so you're likely to be escorted around the 6m-thick ramparts by a policeman or soldier, who'll point out the English canons, surviving watchtowers and ruined belltower. Views across the lagoon are magnificent.
There's a tiny museum with several intriguing items labelled, alas, only in Tamil and you can glimpse the old jail (now a store).
For a great perspective of the fort, head to the tiny Auliya Mosque over the water with its curious green minaret.
