Lotte World Tower, formerly known as the Lotte World Premium Tower, is a 123-floor, 556 metres (1,824 ft) supertall skyscraper currently under construction in the second-generation Lotte World complex in Seoul, South Korea. Upon completion in 2015, it is expected to become the tallest skyscraper in the developed world, surpassing One World Trade Center in New York City and housing the tallest observation deck in the world on its 123rd-floor at 497.6 metres (1,633 ft). After 13 years of planning and site preparation, the tower gained final approval to start construction by the government in November 2010 and the first groundbreaking activities of piling and frame assembly was observed at the construction site on March 2011. The conceptual design calls for a slender cone with convex, gently curved sides. An exterior of pale-coloured glass draws inspiration from Korean ceramics and features accents of metal filigree. Located near the Han River, the tower will contain retail outlets (floors 1-6), offices (7-60), residences (61-85), a luxury hotel (86-119), and public access floors (120-123) with an observation deck. The tower is located next to the existing first-generation Lotte World complex which opened back in 1989, accessible via Seoul Subway Line 2 and Seoul Subway Line 8 on Jamsil Station.