sentences:  In the 1870s, landscape architect Frederick Law Olmsted envisioned a greenbelt across the Bronx, consisting of parks and parkways that would align more with existing geography.This contrasted with Manhattan's grid system, laid out during the Commissioners' Plan of 1811, which had given rise to Central Park, a park with mostly artificial features within the bounds of the grid.However, in 1877, the city declined to act upon his plan.