What are the most worthwhile things to do in Singapore on a first visit?

The Singapore Botanic Gardens charge nothing, every day. The National Orchid Garden inside them is the single exception: open 8:30 a.m. to 7:00 p.m. with last tickets sold and last entry at 6:00 p.m., priced at 15 Singapore dollars for a standard adult, 3 dollars for a senior aged 60 or over and 3 dollars for a student, with lower local rates of 5 dollars, 1 dollar and 1 dollar respectively, and free entry for children under 12. For that you get the largest display of its kind in a garden listed by UNESCO in 2015 under criteria (ii) and (iv) for its contribution to tropical botany and horticulture.

The second anchor is the high view. At Gardens by the Bay, the Supertree Observatory and the OCBC Skyway both run 9:00 a.m. to 9:00 p.m. with last admission at 8:30 p.m., and Floral Fantasy opens at 10:00 a.m. and closes at 9:00 p.m. with last admission at 8:30 p.m. Those evening closing times are generous by the standards of botanical attractions anywhere, and they are the reason a Singapore day can hold a full afternoon elsewhere and still end on a walkway above the trees.

Around those two, a first visit is better served by neighborhoods than by attractions. Chinatown, Little India, Kampong Glam and Katong are each walkable in a couple of hours, and all four are shophouse districts with continuous arcade shade — which, in a climate with no cool season, is a planning fact rather than an aesthetic one.

The Orchid Garden is built across a slope with misted shade houses at the top, so the air changes temperature as you climb. Opening at 8:30 a.m. puts you there before the day's humidity maximum, which in any month peaks above 93%.

The World Heritage inscription covers the Gardens as a cultural landscape — a working botanic garden continuously used for the same purpose since its founding, and the place where Pará rubber was introduced, experimented with and promoted into the plantation crop that transformed Southeast Asia. Fifty-nine Heritage Trees stand inside the property, one tembusu thought to be older than the Gardens themselves. Walking it as scenery misses the point; it is an industrial-historical site with lawns.

• 8:30 a.m. — The Orchid Garden opens, hours before the ticketed attractions at Gardens by the Bay.
• Afternoon — A shophouse quarter on foot, arcades doing the work of shade.
• 8:30 p.m. — Last admission to the Supertree Observatory and the OCBC Skyway, the latest elevated view available.

Several smaller attractions inside the Botanic Gardens close on fixed days — the Jacob Ballas Children's Garden on Mondays except public holidays, the Botanical Art Gallery on the last Thursday of the month, the Heritage Museum on the last Monday. The ticketed attractions at Gardens by the Bay each take one maintenance day a month on staggered dates. The Gardens' own rules rule out some ways of spending a day there: no cycling, scooters or skateboards, no ball or racquet games, no kites or drones, and shelters cannot be reserved for private use.

The places-and-experiences question in this group covers the islands and quarters that fill the days either side of these two gardens.