Much of Olmsted's landscape legacy is architectural rather than horticultural. To distinguish these elements from plantings, modern-day landscape architects coined the term "hardscape."
In 1874, Frederick Law Olmsted was charged with devising a comprehensive landscape scheme for the U.S. Capitol. Olmsted's major concern was the visual presentation of the Capitol Building and the support of its daily functions. In his submission for the Architect of the Capitol's annual report, Olmsted wrote that, "the ground is in design part of the Capitol, but in all respects subsidiary to the central structure."
Hardscape elements include the low walls bordering the walks and roads and the various lamps needed for lighting the grounds at night. Some of Olmsted's significant hardscape elements can be found on the East Front plaza of the U.S. Capitol. Restoration and modernization work was completed as part of the building of the Capitol Visitor Center. The fountains and lanterns are fully modernized, and new technologies, such as the fountain's water pressure levels, are tied to an anemometer that lowers the water pressure as winds rise.
The terrace walls that wrap around the Capitol to the north, west and south are constructed largely of Lee Massachusetts marble with a granite rubble foundation. The center west portion and balustrades are constructed of Vermont marble. The terrace was designed to provide a strong visible architectural base to the Capitol and heighten the grandeur of the building. It extends approximately 1,600 lineal feet and rises about 20 feet in height at its highest point.