ABRAJ AL BAIT TOWERS www . facebook . com / Abraj . al . Bait . Official / Located in Mecca , Saudi Arabia , Abraj Al Bait Towers , also known as the Mecca Royal Hotel Clock Tower , is the most expensive building in the world . Its construction cost is about $ 15bn , according to Express . With 601m in height , 1,500,000 sqm in floor area , and a 100,000-person capacity , it is the world ’ s tallest hotel , designed by Lebanese architecture group Dar Al-Handasah . The upper clock tower was designed by German firm SL Rasch . Commissioned by Saudi Binladin Group it consists of seven towers , according to Construction Week Online . It took 10 years to build , according to Skyscraper Centre , with construction started in 2002 , and finalised in 2012 . Although previously more expensive due to material costs and bans , Reuters reports that construction costs in Saudi Arabia in recent years have fallen between 10 and 15 % per sqm . 58 February 2018