What's the must-see thing in Singapore?

The Supertree Grove at Gardens by the Bay is free to walk through at ground level, and at night it's the single most distinctly Singaporean sight you can experience. The trees — sixteen vertical gardens wrapped in steel lattice, the tallest reaching 50 metres — light up during the Garden Rhapsody show at 7:45pm and 8:45pm nightly. You'll feel the warm concrete underfoot still releasing the day's heat, smell frangipani from the planters circling the grove, and hear the orchestral soundtrack bounce off the glass domes of the Cloud Forest and Flower Dome conservatories behind you. The OCBC Skyway, a 128-metre elevated walkway strung between two of the tallest Supertrees, costs S$14 (about US$11) and is worth every cent. Book your slot online for 7:15pm so you're already up there when the lights start beneath your feet.

If you only have one morning, walk the Marina Bay waterfront loop. Start at the Merlion on the south bank — yes, it's the tourist photo op, but it's also the spot where you can see the Marina Bay Sands hotel, the Esplanade's durian-shaped roof, and the financial district towers all in one frame. The loop runs about 3.5 kilometres from the Merlion around to Gardens by the Bay, and at 7am before the humidity passes 60%, the breeze off the water still feels cool on your arms. By 10am the pavement radiates heat and the shade vanishes. The SkyPark observation deck on top of Marina Bay Sands (S$32, timed entry) gives you the reverse angle — the whole city grid spread below, with container ships lined up in the strait beyond Sentosa. That view is the one that tells you where everything else is.

For the cultural weight of the trip, head to the Buddha Tooth Relic Temple and Museum on South Bridge Road in Chinatown. The building opened in 2007 — a Tang dynasty-style complex with a 420kg gold stupa on the fourth floor housing a tooth relic. Free entry. The ground floor fills with the thick, sweet smell of sandalwood incense, and on weekday mornings you might hear monks chanting from the prayer hall while visitors stand quietly along the walls. Chinatown itself is two-sided: the shophouses along Pagoda Street sell cheap souvenirs, but Smith Street has proper wonton mee and char kway teow at S$5–8 a plate. That said, Maxwell Food Centre two blocks south is the better hawker centre — fewer tourists, more office workers eating their actual lunch there. Get the Tian Tian chicken rice if there's a queue; skip it if there isn't, because something is off.

A note on what to skip your first time. Sentosa Island and Universal Studios Singapore eat an entire day for a theme park experience you could have in Osaka or Orlando. The Singapore Flyer, a 165-metre Ferris wheel near the bay, gives you a worse view than the SkyPark at a higher price. Haw Par Villa in the western suburbs — a park of lurid dioramas depicting Chinese mythology's tortured sinners and demon judges — is unlike anything you'll find anywhere else, and it's free, but the transit time from the centre runs close to an hour each way. Save it for a return visit. Your first 48 hours belong to the Marina Bay–to–Chinatown corridor. Everything that makes Singapore specifically Singapore sits within a 4-kilometre walking radius there.