People enjoying hotpot inside an igloo in Harbin in China's north-eastern Heilongjiang province, during the annual Harbin International Ice and Snow Festival. The festival, featuring glittering palaces and fantastical scenes sculpted out of ice, has drawn millions of people over the years to one of China's coldest cities. This year's event required 170,000 cu m of ice taken from the Songhua River by more than 100 workers. They toiled for hours on the ice each day in the weeks before the festival, cutting out thousands of pieces of ice in 12-hour shifts.