Winter definitely made itself known this week, with frigid temperatures hitting cities across America. Meanwhile, as the Hudson River was left covered in ice, across the pond, Prague saw unseasonably warm weather. Although temperatures seemed to dominate headlines, the week also saw special events in politics, sports, and fashion. The Duke of Cambridge went to, well, Cambridge to head back to school, Serena Williams celebrated a big win in Australia, and racers took to the Grand Canal for a tradition in Venice. See all that and more with the week's best pictures from around the world!