Forty boundary stones, made of Aquia freestone, originally marked the four sides of the diamond-shaped square of the District of Columbia, North, South, East and West. The stones were square with a pyramid shape at the top and were laid out, each stone a mile apart, by Benjamin Banneker and Major Andrew Ellicott between 1791 and 1792. On the sides facing the states, the names of the states were inscribed. On the opposite side were the words "Jurisdiction of the United States." These boundary stones are the oldest federal monuments in the United States.
The White House was built using Aquia sandstone but the stone was painted white. After the War of 1812, when the White House was burned, the structure was washed and cleaned but more of the Aquia freestone was brought in to restore the building.
Parts of the Capitol building are built with Aquia sandstone including the original gatehouses which can now be found at Constitution Ave and 15th and 17th Streets in Washington. The stone is unpainted and the original color can be seen.