Planners didn't realize this until a history buff, Edward Lawler Jr., told them this January that the building would cover the building that served as the executive mansion (the predecessor to the White House) for George Washington and John Adams, and the buildings that housed eight of Washington's slaves during his presidency.
Washington brought the eight slaves with him to tend his household while he was president. Pennsylvania had outlawed slavery, but Washington got around the law by declaring himself a Virginia resident only temporarily staying in what was then the capitol.
Gary B. Nash, professor emeritus at UCLA, is one of the historians who took up the cause of getting the Park Service to pay attention to this piece of history. Nash's books about early America, about Philadelphia and about race are widely used in university history courses.
"It's all about managing memory, manipulating memory, and in some cases, memory is murdered," he told me.
In this case, memory is about to be buried along with the physical artifacts of our country's early days. Nash and fellow scholars couldn't hold off construction long enough to excavate the site, but after months of pleading , they did get the Park Service to agree this month to amend its interpretive plan to include a serious discussion of the site and of the interplay of slavery and freedom in early America.
A few days after the agreement was worked out, Nash dismissed the inevitable criticism that somehow mentioning slavery would turn visitors against America. He told me about two of Washington's slaves who escaped while the president was in Philadelphia. "These are liberation stories," he told me, "people pursuing what the Founding Fathers said the country was based on: freedom."
Nash grew up in Philadelphia. He said a good friend of his, who is African American, recalled learning in school about George Washington Carver and his peanuts. He asked the teacher if there weren't some other African Americans who contributed to the nation. "She said, 'No, Charles, there aren't any.' "
Nash laughed when I told him how often I'd heard someone say that history is the one subject in which, when you get to college, you are told to forget everything you've been told to at that point, because it was wrong.
He laughed because he's said that a few times himself, but he has also tried to do something about it. Nash is director of the National Center for History in the Schools, which creates curriculum and endeavors to help classroom teachers master history and pass it along to their students.
I asked him about the nation's report card. That's the report on the National Assessment of Educational Progress, which showed again this year that most American students don't know much about history.
Nash said history texts are better now than ever, more inclusive and therefore more accurate, but too often, the people teaching history have no background in the subject and barely know more than their students.
Nash said his son teaches high-school physics and had to have mathematics credentials to do so, but there is no similar requirement for history teachers to have any specialist credentials. That's not good, because history is not a simple subject. Students can be left with dates and names and myths instead of a vibrant, contentious reality.
Nash's latest book, "The First City: Philadelphia and the Forging of Historical Memory" (University of Pennsylvania Press), explores how we decide which history gets told.
Too often, we've celebrated one part of our history at the expense of the rest. At our nation's birth, 20 percent of the population was African American, Nash said, and yet the story of freedom was going to be told with barely a mention of their quest to be free.
Nash said we have a government that is by the people, for the people and of the people — so, he asks, "Why not have a history of the people, by the people and for the people — all of them — a history that is democratic."
It's time to stop burying parts of the American story.