Dubai is hot. Summer temperatures can easily exceed 110 degrees Fahrenheit, and desert conditions can mean weeks without relief. The city is already home to a slew of all-weather venues, such as Ski Dubai, the Middle East's first indoor ski resort, but the UAE's latest project could bring comfort to millions of residents and annual visitors. Mall of the World, as the complex is to be named, will include 20,000 hotel rooms, making up some 100 hotels and apartment complexes, the world's largest indoor theme park, an 8-million square foot mall and a 3-million square foot "wellness district," with doctors and inpatient facilities for medical tourists.

With nearly 4.5 miles of temperature-controlled streets with ceilings that can open during the mild winter, complete with trollies, escalators and all the shopping you could hope for, residents will never have to step outside. Underground parking will accommodate some 50,000 cars, and a variety of cultural venues will attract locals and those living outside, alike. It's an ambitious project, and an opening deadline has yet to be named, but if any city can pull off such a retail mecca, it's Dubai.