Palakkad Fort is the town's best monument and a useful place to understand why this otherwise quiet inland city mattered. The laterite walls, moat and gateways are in unusually good condition for a town-centre fort, and the surrounding maidan gives it breathing space.
It is not a sprawling ruin that needs half a day. An hour is enough for most visitors, longer if you want to sit in the shade and watch the town move around it. Go early or late, when the stone is cooler and local families come out for a walk.