George Kessler's 1907 park and parkway master plan made Speer Boulevard the key diagonal. It follows Cherry Creek from University Boulevard to the creek's confluence with the South Platte River and then crosses the river and the tracks on a viaduct into northwest Denver. Jerome Smiley, in his History of Denver (1901), described Cherry Creek as a “miserable and sandy waste” lined with dumps and used as a sewer. Kessler's imaginative plan transformed the creek into the centerpiece of a tree-lined boulevard. The plan left little triangular land parcels where this only major diagonal in the city met the grid. Some of these have been dedicated as mini-parks complementing several larger parks along Speer Boulevard.
Designation of Speer Boulevard in the 1980s as both a National Register and a Denver landmark ended the street widening that had reduced its grassy, tree-shaded edges. Restoration of the historic lighting, bridges, and landscaping on Speer stimulated restoration of the entire parkway and park system along City Beautiful lines. Various ramps off Speer lead to a paved creek-side trail to Denver's birthplace, Confluence Park. One of the loveliest stretches of the Cherry Creek Greenway is Creekfront Park (1992, Robert Karns) at Speer Boulevard and Larimer Street, with a water garden and a path from downtown under Speer to the Auraria Higher Education Center campus.