HALLANDALE BEACH, Fla. -- With its fast food restaurants, churches and strip malls, this city in southeast Florida looks like much of America. But on a sunny day last month, city official Hector Castro talked about its resemblance to Italy's slowly sinking Venice. "At some point in the future, some places may be uninhabitable," said Castro, director of the city Department of Public Works, Utilities and Engineering. "Maybe people could live in the top part of buildings. But what do you do about the roads?"