Man-made islands; indoor ski slopes; temporary ice hotels. We thought we had seen it all in Dubai, and then the Middle Eastern city went and outdid itself with the Water Discus Hotel, a hotel that will feature a series of sci-fi styled discs, one of which will be located 21 stories underwater. For those who prefer to stay above water, Antwerp will open one of the world’s largest floating swimming pools this summer. Made from an old ferry boat, Badboot will be 120 meters long and it’ll be part of a larger facility that can host as many as 600 people. And across the point in New York, the One World Trade Center skyscraper was just crowned the tallest building in NYC.