Upscale restaurants, majestic theaters, and luxury condos line the streets of downtown Boston today. Students, office workers, doctors, and shoppers navigate the busy sidewalks along Washington and Boylston Streets, giving little thought to the historical significance of their surroundings. The bustle distracts passersby from what may be the city’s dirtiest little secret: these blocks were once home to Boston’s most notorious neighborhood. The Combat Zone, a five-plus-acre, city- sanctioned adult entertainment district, was as sordid and alluring as anything found in Amsterdam or Vegas. Indeed, Boston’s now tony neighborhood once resembled the set of HBO’s The Deuce, all with the blessing of city officials.