To Do Monday: Lower Manhattan History Lesson

There was a time not too long ago when candidates for public office in America might downplay time spent in a foreign land battling alongside communist revolutionaries. But in the brave new world of brave New York, the front-runner in next week's Democratic primary, Bill de Blasio, cites "his graduate years with a pro-Sandinista humanitarian organization in Nicaragua" among his many qualifications for the city's top job. Today, unleash your inner socialist with a Labor Day stroll through Lower Manhattan. With Big Onion Walking Tours as your guide, amble through historic neighborhoods like the East Village and the Lower East Side, erstwhile working-class slums whose swank modern bars and restaurants betray little about the past if you don't know what to look for.