This fort was built by the Dutch to compensate for deficiencies in the neighbouring rampart, but it’s so small it could only have protected a handful of bureaucrats. Look out for the construction date (1765) embossed over the main gate, along with VOC insignia and the coat of arms of the governor of the day. Inside there's a small museum with modest displays about the history of Matara, and you can view former soldiers' sleeping quarters and prisoners' cells.
Look for the two carved lions that guard the entrance gates and then stroll the mini-ramparts, complete with cannon stations.