Short answers, pulled from the story.
Jewel Changi Airport is a nature-themed entertainment and retail complex linked to Terminals 1, 2, and 3 of Changi Airport in Singapore. It sits in Changi, at the eastern end of Singapore, about 20 kilometers northeast of the city's Downtown Core.
Jewel Changi Airport was officially opened by Prime Minister Lee Hsien Loong on the 18th of October 2019, six months after its soft opening. Within that first stretch it had already drawn 50 million visitors, ahead of an initial target of 40-50 million for the year.
A consortium of architects led by Moshe Safdie, who also designed Marina Bay Sands, designed Jewel's toroidal glass-and-steel facade. RSP Architects Planners & Engineers served as executive architects and structural engineers, while PWP Landscape Architecture handled the landscaping and WET Design engineered the Rain Vortex.
The Rain Vortex stands 40 meters high, making it the world's tallest indoor waterfall. Recirculated rainwater falls through a round hole in the roof at up to 37,850 liters per minute into a basement-level pool.
The project cost S$1.7 billion, developed by Jewel Changi Airport Trustee Pte Ltd, a joint venture between Changi Airport Group and CapitaLand. No government funds or taxpayer money were used, even though both companies are partly or wholly owned by Singapore's state investment firm, Temasek Holdings.
Jewel was conceived to keep Changi Airport competitive as a major aviation hub in the Asia-Pacific region. Prime Minister Lee Hsien Loong first raised the idea in his 2013 National Day Rally speech as part of a plan to double the airport's capacity by the mid-2020s.