ou know about the Freedom Trail. Here’s the freedom trail you haven’t heard about. The Black Heritage Trail commemorates the affluent free black community that settled on Beacon Hill, where seeds of abolition grew. Like the history it chronicles, this 1.6-mile route, through the neighborhood that now is Boston’s most elite address, is steep and uneven. It shows Boston’s troubled history with race, beginning as it does with the 1897 Robert Gould Shaw 54th Regiment Memorial in front of the State House, commemorating the all-black Civil War company from Boston that was the subject of the movie Glory. You know the one. But here’s something else you didn’t know: When it was built, the monument bore only the names of the regiment's white officers; the names of blacks who died were not added until 1982. Marcus