Located in the northwestern neighborhood of Washington Square, this was one of the city’s earliest public parks, created within a three-acre vacant lot on the southeast corner of El Molino Avenue and Washington Boulevard that was purchased in 1920. In 1922, landscape architects Ralph Cornell and Theodore Payne completed a plan for the park and its "sunken gardens." The site, a natural stream basin, had irregular terrain, which the designers leveraged with the incorporation of pathways, river rock walls, native plants, a rustic stone bridge, a tennis court and small playground. In the 1940s, the Works Progress Administration constructed a stone wall and an additional 2.1 acres were purchased, making space for a softball diamond, a new playground, and a parking lot. Basketball and handball courts and adult exercise equipment were added over time.
In 2003, the city, in partnership with the Friends of Washington Park and the Theodore Payne Foundation, selected landscape architects Troller Mayer Associates, Perry & Associates, and Onyx architects to implement an updated master plan, which included retaining and enhancing the historic look and feel of the park, and a focus on the use of local native plants. Also included were a stone stage, accessible pathways, and native plant demonstration gardens, all completed in 2006.