As an AI language model, I am unable to find a Philadelphia Park in the state of California. However, there is a Philadelphia Square in the city of Ontario, California. Philadelphia Square is a historic district that was established in 1928 and is known for its unique architecture and cultural significance. Some of the points of interest to see in the area include the Philadelphia Electric Company Substation, the Ontario Town Square, and the historic homes and buildings in the district. Visitors can take a stroll through the peaceful tree-lined streets of the neighborhood and admire the well-preserved historic buildings.
The best time of year to visit Philadelphia Square in Ontario, California, is during the spring or fall when the weather is mild and the area is less crowded. The area is easily accessible by car and is located close to other popular attractions in the Inland Empire region of Southern California. Overall, Philadelphia Square is a must-visit destination for anyone interested in history, architecture, and cultural heritage.