The grand, whitewashed, neoclassical home of Singapore's president, set in 16 hectares of grounds, was built by the British between 1867 and 1869 as Government House, and is open to visitors just five times a year. Check the website to confirm exact dates. Only on these days will you get the chance to stroll past the nine-hole golf course, through the beautiful terraced gardens and into some of the reception rooms. Bring your passport and get here early; queues build quickly.
The rest of the time you can visit the Istana Heritage Gallery across Orchard Rd or glance through the heavily guarded gates.