Here’s a bit of local trivia from a native: The Washington Monument was originally intended to be at the geometric center of DC, at the intersection of lines running through the centers of the White house and the Capitol. Thomas Jefferson ordered a marker to be placed at that point, hence the name. The ground there was too soft to support such a massive structure, so the Monument was constructed at the top of the hill. There is a small marker on the spot, unknown and unnoticed by most. In fact, even the park ranger I asked didn’t know where it is!