Kota Tua (Old Batavia) is the best half-day. This cobbled Dutch colonial square holds the Jakarta History Museum, the puppet museum and Cafe Batavia. Rent a colourful bicycle on the square, then walk 10 minutes to the old Sunda Kelapa harbour to see tall wooden schooners still loading cargo.
Monas (National Monument) is the 132 m torch-topped tower in Merdeka Square. Ride the lift to the observation deck for a city panorama; entry costs under Rp35,000 (about $2). Go on a clear morning — afternoon haze kills the view.
Ancol Dreamland on the north coast bundles Jakarta's family fun: Dunia Fantasi (Dufan) theme park, Sea World aquarium and Atlantis water park. Each needs its own ticket, so pick one or two rather than trying all three.
Taman Mini Indonesia Indah shows the whole country in one park — full-size traditional houses from every Indonesian province, plus a cable car over the grounds. It is far from the centre, so treat it as its own half-day.
For a break from sightseeing, Jakarta's malls are an attraction in themselves — Grand Indonesia and Plaza Indonesia sit in the centre and are good rainy-afternoon or food-court stops. Istiqlal Mosque, Southeast Asia's largest, stands directly opposite the Catholic cathedral and welcomes respectful visitors outside prayer times.