Visiting this observation deck on level 56 of the ION Orchard complex used to be free. However a spruce up, which includes an informative multimedia show, means you can only gain entry by spending S$20 per person in one day at the shopping centre. Once you've emptied your wallet, visit the concierge counter to collect a ticket and book a slot. The view is spectacular, especially on a clear day, making it (just) worth the rigmarole of securing a ticket.
Entry times are every 45 minutes from 2pm to 5pm and from 7pm to 7.45pm, and each admission lasts for 45 minutes.