To find the 1915 Panama-Pacific International Exposition’s legacy in San Francisco, proceed to the Palace of Fine Arts. Then start thinking like a detective.

Why the Palace of Fine Arts? Because that lagoon-adjacent building (3301 Lyon St.) is the only major 1915 expo structure still in its original location. The palace, a crowd favorite from the start, stood mostly on public property (which made it easier to save), and unlike most expo buildings, it was built with steel framing, not wood.

Another difference was its design — romantic — while other expo "palaces" followed Beaux-Arts style, relying on lighting to provide splashes of color.

"The more I actually studied the building," said historian Laura A. Ackley, author of "San Francisco’s Jewel City: The Panama-Pacific International Exposition of 1915," "the more I realized it’s an absolute tour de force of brilliant architecture."

The palace is best known these days as a performing arts venue, but to mark the expo centennial, it will house a California Historical Society exhibition on the fair from Feb. 20 to Jan. 10.

Another display in the palace, called "Innovation Hangar," celebrates the spirit of innovation in the city. Also, San Francisco City Guides (www.sfcityguides.

org) offers tours of the Palace of Fine Arts and of the Marina District, with much of the script devoted to the 1915 expo.

Now the detective work. Although most of the expo buildings were leveled, one replica was built, two grassy areas retain footprints of the fair, some artwork has been relocated and there are exhibitions and books as well.

The Legion of Honor building (100 34th Ave., Lincoln Park), now part of the Fine Arts Museums of San Francisco, is a double replica, twice removed. It was built in 1924 (three-quarter scale) as a facsimile of the 1915 expo’s French Pavilion, which was itself a facsimile of a Paris landmark dating from 1788. In fact, the original Palais de la Legion d’Honneur still stands in Paris on Rue de Lille in the 7th arrondissement.

The Marina Green, along Marina Boulevard, was known during the expo as the North Gardens. Back then kids danced there and a plane took off. These days, Ackley said, you look across the street to a row of 1920s homes. During the expo, "You’d be looking at a 65-foot-tall ivory-colored wall," with intricate portals, complemented by flags and domes.

Crissy Field (along Old Mason Street between the Warming Hut and Crissy Field Marsh) was the western edge of the expo. In fact, work crews carted in sand, mud and silt to cover marsh and dunes for a dry, even surface for racing. The area included an 18,000-seat grandstand, an oval for car racing and horse racing, and a running track and athletic field inside the oval. After the expo it became a military airfield. Now it’s a grassy expanse that’s part of Golden Gate National Recreation Area. It has views of the Golden Gate Bridge, which didn’t go up until 1937.

In Golden Gate Park, near the Pioneer Log Cabin, stands a bronze statue, "Pioneer Mother," by Charles Grafly. The artist produced it for the expo, and it was also part of the Golden Gate International Exposition (on the city’s Treasure Island) in 1939 and 1940. The sculpture has been in its current location since 1940.

The 1915 expo’s Court of Ages included eight massive murals on canvas — each 12 by 27 feet, depicting earth, air, fire and water — by painter Frank Brangwyn. In 1932 they were mounted on the walls of the War Memorial performing arts center’s Herbst Theater, and there they remain. The theater is closed for renovation, with the murals covered by plywood until a reopening in the fall.

The California Historical Society (678 Mission St.) will stage an exhibition on the expo from Feb. 22 to Dec. 6, "City Rising: San Francisco and the 1915 World’s Fair."

The society is also part of a show at the de Young Museum, 50 Hagiwara Tea Garden Drive, that displays 250 artworks from the 11,000 that were at the original expo, including some murals on canvas that haven’t been seen for years. The show will run from Oct. 17 to Jan. 10.

By Christopher Reynolds, Los Angeles Times