These are the oldest federal monuments in the USA.
Constitution-class warships
Mount Vernon home and lands
District of Columbia Boundary Stones
Monuments at Gettysburg
D.C. Boundary Stones. Beginning Apr. 15, 1791, surveyor Andrew Ellicott and his team spent two years clearing the boundary within which America’s capital was to be built. They laid one boundary stone every mile, 38 of which are still in or near their original positions.