A small wooded hill at the northern edge of the town centre, Gunung Kunci — "Key Mountain" — was fortified by the Dutch in the nineteenth century as a defensive position overlooking the surrounding valley. The old stone bunkers and earthworks are still visible, embedded in a municipal park that locals use for morning walks and weekend picnics.
The climb takes only ten or fifteen minutes and the summit offers a reasonable view over the town and the rice fields below. It is not a dramatic destination — no cable car, no café at the top — but the colonial fortifications are quietly interesting, and the shade makes it a sensible stop during the hot middle of the day. Combined with the museum and the alun-alun, it rounds out a decent two-hour loop of central Sumedang.