In a photo provided by the Changi Airport Group, the Forest Valley and Rain Vortex waterfall inside the Jewel at Changi Airport in Singapore. The 10-story Jewel, offering visitors a forest, indoor waterfall and more than 280 stores and restaurants, hopes to make the Singapore airport a destination in itself. (Changi Airport Group via The New York Times) — NO SALES; FOR EDITORIAL USE ONLY WITH NYT STORY SINGAPORE AIRPORT JEWEL BY SANJAY SURANA FOR APRIL 11, 2019. ALL OTHER USE PROHIBITED. —