SAN FRANCISCO -- Anniversaries are meant for families to celebrate, so it was fitting that the descendants of the Giants' true patriarch were on hand Tuesday for the club's latest celebration revolving around its 50th year in San Francisco.

A plaque commemorating the first Major League regular-season game played on the West Coast exactly 50 years ago -- April 15, 1958 -- was dedicated on the corner of 16th and Bryant streets, site of Seals Stadium, the Giants' first San Francisco home. The Giants defeated the Los Angeles Dodgers, their fellow East Coast transplants, 8-0, that afternoon.

Among the honored guests were grandchildren and great nieces and nephews of Horace C. Stoneham, whose family owned the Giants from 1919-76. Stoneham took over the club from his father, Charles, in '36 and continued to base it at New York's Polo Grounds before the move West.

Pete Stoneham knows that his grandfather, who died in 1990 at age 86, would have relished seeing the Giants flourish at AT&T Park. The Giants have exceeded three million in paid attendance for eight consecutive seasons since their current downtown home opened.

"To see the crowds we have here, as opposed to the 800, 900 people at night games at Candlestick Park in the '70s, I think he'd be very proud because the franchise is going strong," Stoneham said.

Horace Stoneham was part of the end of an era when families, not corporations or investor groups, owned sports franchises. He was always known for his first-class treatment of Giants players.

"A lot of people criticized his executive skills. But he was a good person," Pete Stoneham said. "This was his family. As Willie [Mays] said earlier today, he was like his father."

Other distinguished attendees at the plaque-dedication ceremony and pregame festivities at AT&T Park included Helen Christopher and Ethel Davies, the sisters of San Francisco mayor George Christopher, who was instrumental in bringing the team to northern California.

"He used to fly to New York at midnight so the press wouldn't question him," Helen Christopher recalled.

Christopher remained a passionate Giants fan until his death in September 2000 at 92.

"The night before he died, he had the game on and he wanted to know the inning and the score," Helen Christopher said.

Orlando Cepeda, the Hall of Fame first baseman who broke into the Majors with San Francisco in 1958, and Gino Cimoli, the Dodgers' leadoff hitter for the inaugural West Coast game, threw ceremonial first pitchers before the Giants-D-backs game.

The plaque embedded at 16th and Bryant, dated April 15, 2008, reads:

"On this date 50 years ago today, Major League Baseball on the West Coast became a reality when San Francisco Giants pitcher Ruben Gomez threw the first pitch to the Los Angeles Dodgers' Gino Cimoli at 1:34 p.m. on April 15, 1958 at Seals Stadium.

"Since defeating the Dodgers 8-0 that afternoon to embark on the San Francisco era of Giants history, the club has won three National League pennants and six National League West titles.

"In the first 50 years of San Francisco Giants baseball, Willie Mays, Willie McCovey, Juan Marichal, Orlando Cepeda and Gaylord Perry have been enshrined in the Hall of Fame as Giants.

"The Giants have enjoyed three homes in their first 50 years in the City by the Bay, playing here at Seals Stadium from 1958-59, Candlestick Park from 1960-99 and AT&T Park since 2000."