Each winter, The Red and Assiniboine rivers that run through the Canadian city of Winnipeg freeze over as the temperature drops to around minus 30 degrees, the city authorities plough the frozen river clearing it of snow to create skating trails for the citizens. This winter has seen the construction of a cluster of skating shelters by Patkau architects, each formed of thin, flexible plywood that deflect the harsh winds that can make minus 30 feel like minus 50, providing a haven from the elements for the most dedicated of skaters.