Before Hurricane Sandy, building giant sea walls to protect NYC from storm surges may have sounded extreme, but now respected urban planners are considering it as a viable solution. The New York Observer recently spoke to Vishaan Chakrabarti, the director of Columbia’s Center for Urban Real Estate and a partner at SHoP architects, who says that building-sized floodgates like the ones that guard areas of Rotterdam from flooding are one answer that could save billions of dollars in damaged property.