From Zaha Hadid's bulbous plaza to a ‘library' of flora planted across a skygarden, the South Korean capital is using its architecture festival to look to the future – and atone for the costly sins of the past
Everything you need to build a nuclear submarine can be found in Sewoon Sangga, or so they used to say. Walking the labyrinthine levels of this concrete megastructure, which sweeps through the centre of Seoul like a convoy of container ships almost a mile long, it's not hard to believe.
In one of the complex's open-fronted workshops, a man glides a plasma cutter through a thick steel plate while someone else welds tubes into a cage. On the floors above, between units selling everything from jars of lenses to covert surveillance cameras and refurbished arcade machines, people solder circuit boards. It is a kaleidoscopic cross-section: florists rub shoulders with attorneys, record shops with private security firms, counterfeit Viagra sellers with the HQ of Mr Silver Korea, a competition for ageing bodybuilders.