Building Stones of Our Nation's Capital Washington's
Building Stones of Our Nation's Capital: Washington's Building Stones [4 of 4] The masonry locks of George Washington's Potowmack Canal at Great Falls, Va., are largely constructed of this Seneca red sandstone, as are many of the locks, lockhouses, and other structures of the Chesapeake and Ohio Canal, which were built between 1828 and 1850.