Balboa Park is a 1,200-acre urban cultural park in San Diego, California, United States. In addition to open space areas, natural vegetation zones, green belts, gardens, and walking paths, it contains museums, several theaters, and the world-famous San Diego Zoo. Named for the Spanish maritime explorer Vasco Núñez de Balboa, the park hosted the 1915–16 Panama–California Exposition and 1935–36 California Pacific International Exposition, both of which left architectural landmarks. The San Diego Model Railroad Museum is a model railroad exhibit in San Diego, California. At 27,000 sq. ft., it is the largest indoor such exhibit in North America, and one of the largest in the world. The museum is on the lower level of the Casa de Balboa on the Prado in Balboa Park. The museum is open Tuesday – Friday 11 am to 4 pm, Saturday and Sunday 11 am to 5 pm.