On Monday evening, Michelle Obama’s speech at the Democratic National Convention received critical acclaim for its tone and message, as well as extensive coverage of one of her closing lines—"today, I wake up every morning in a house that was built by slaves." Juxtaposed with an image of her daughters playing in the White House Lawn, the line summarized the scope of social progress in the United States.

Obama’s oratory underscored an uncomfortable part of our capitol's, and nation’s, past. But the White House was far from the only structure in D.C. that was built, at least in part, utilizing then-legal slave labor. It’s a fair assumption that many larger buildings in the early years of the colonies and the country, as well as the antebellum south, may have been built, at least in part, with slave labor (over the last few years, many schools and institution are currently wrestling with the question of what to do with Confederate-era monuments).

Here are a few examples of how slave labor factored into construction of some of the nation's early landmarks, the stories of some of these laborers, who in many cases were skilled artisans, and how modern-day institutions are discussing, and in many cases memorializing, this chapter in history.