Not everything that Tweed touched was bad. Under his reign, Central Park, Frederick Law Olmsted's masterpiece of urban landscape, was completed. Creating this pastoral setting required shifting nearly 5 million cubic yards of dirt, blasting rock with 260 tons of gunpowder and planting 270,000 trees and shrubs. Completed in 1864, visitors to Central Park still enjoy vistas across the sheep meadow, strolling along wooded paths and people-watching on the terraces and promenades that Olmsted and his collaborator, architect Calvert Vaux, provided. Olmsted was born April 26, 1822.

In 1874 he was commissioned to plan and oversee the renovation of the U.S. Capitol grounds. He had marble terraces constructed on the north, west and south sides of the building to cause it to "gain greatly in the supreme qualities of stability, endurance and repose." He developed an architectural treasure known as the Summer House (on the north side of the Capitol grounds) to give visitors a meditative place to rest, planted more than 7,000 trees and shrubs along with other vegetation and laid curved footpaths and roads across the grounds. He also employed ornamental iron trellises, low stone walls and light stands for functional and decorative purposes. Olmsted retired from supervising the terrace project in 1885 but continued until 1889 to direct work on the grounds.