It will include gardens and attractions, a hotel, aviation facilities and 300 retail and dining facilities. The complex covers a total gross floor area of 134,000 m, spanning 10 storeys – five storeys above-ground and five basement storeys. Attractions will include the Rain Vortex, the world’s largest indoor waterfall; the Forest Valley, an indoor garden spanning five storeys; and Canopy Park at the topmost level, featuring gardens and leisure facilities.

The complex was built to improve the competitive position of Changi Airport against rivals such as Kuala Lumpur International Airport and Bangkok’s Suvarnabhumi International Airport. Jewel was first mentioned by Prime Minister Lee Hsien Loong in his National Day Rally speech in 2013. He announced the plan to build Jewel as part of Changi Airport’s long-term plans to double its current capacity and “create many more opportunities for Singapore”.

Built over the former open-air car park in front of Changi Airport Terminal 1, the completion of Jewel in 2019 will see the expansion of Terminal 1’s arrival hall and baggage claim areas by 70%. Terminal 1’s handling capacity will also increase from 21 to 24 million passengers a year.

According to wikipedia