It was once half of the Stonewall Inn, the dive bar where a police raid exploded into a landmark moment for LGBTQ+ rights movement. Yet for much of the 55 years since, there has been little outward indication that 51 Christopher St. was part of that history. When a new Stonewall Inn opened in parts of its old habitat, the space at 51 Christopher became a bagel shop, a clothing store, a nail salon, then vacant space. But on Friday the building will open as the new visitor center for the Stonewall National Monument on the anniversary of the 1969 rebellion that helped reshape LGBTQ+ life in the United States.