Jewel Changi Airport, Singapore

Moshe Safdie's Jewel Changi Airport (2019) houses the world's largest indoor waterfall — the 40-metre Rain Vortex — at the centre of a donut-shaped glass and steel structure containing a forest of 2,000 trees, 100,000 plants, and retail space. The ETFE dome harvests rainwater for the waterfall, which is also used for cooling. It is simultaneously the world's most spectacular airport terminal and a functioning ecosystem.