Built at a cost of SG$1.7 billion (about US$1.25 billion) and designed by renowned architect Moshe Safdie, Jewel has 10 stories -- five above ground and five in the basement. The star attraction is the 40-meter-tall (around 130 feet) HSBC Rain Vortex, which cascades through a huge oculus in the middle of Jewel and is billed as the world's tallest indoor waterfall. It's a dramatic site that's usually heard before it's seen as passengers exit the retail and dining zones that wrap around the Jewel's outer sections and head toward the center, where they're met with the thunderous sounds of a waterfall that appears to fall from the sky. But the new Changi addition serves multiple purposes for travelers. In addition to linking Terminals 1, 2 and 3 (passengers heading to and from Terminal 4 need to take a shuttle bus), offerings include early check-in services and baggage storage facilities as well as a 130-cabin YOTELAIR Singapore Changi Airport hotel. There's also the Changi Lounge, designed to complement a new intermodal transfer service that improves air-sea connectivity for cruise passengers. Beyond expected amenities like free Wifi, Jewel offers a few little nice touches like power bank loans -- free for 12 hours. There are plenty of diversions for travelers stuck in Changi on a long layover, too, including an 11-cinema IMAX theater. Jewel's Shiseido Forest Valley is a four-story garden filled with walking trails set amid more than 235,000 square feet of landscaping, all surrounding the Vortex waterfall. "Rainwater is collected and it becomes a part of the Vortex as well," Jayson Goh, managing director for airport operations management of Changi Airport Group, tells CNN Travel. "We can actually control the volume of flow. Below the Vortex we have tanks to collect the rainwater so that we can recycle it. When there's an excess of rainwater, it can be used for irrigation of the plants in the Forest Valley." A Skytrain, which connects Changi terminals 1, 2 and 3, cuts through the middle of the Jewel, passing by the Vortex and adding to the photogenic scene. On the top floor is the 14,000-square-meter Canopy Park, which has several restaurants and themed gardens. Though some sections are open, work is still underway on this one. The park's Canopy Mazes, Sky Nets, Discovery Slides and 50-meter Canopy Bridge won't be ready until mid-2019. The back story behind Jewel's development is basically Joni Mitchell's "Big Yellow Taxi" in reverse. Changi Airport Group has essentially turned a parking lot into an indoor paradise, inspired by Singapore's reputation as a "city in a garden." "Back in 2010 we were looking at expanding the capacity of Terminal 1 and we decided that the open-air parking structure could potentially become a new integrated complex," says Goh. That car park was transformed into the stunning space that now stands in its place, a marvel for those who have been following Jewel Changi Airport's progress since 2013, when news of the airport expansion -- then simply named "Project Jewel" -- first broke. Given that the architect behind the project is Moshe Safdie, at the time already famous for designing another Singapore icon, Marina Bay Sands, hopes were high that he would deliver an equally impactful building.