City officials, 49ers executives and hundreds of construction workers watched as the beams -- one holding an American flag, the other a Christmas tree -- were bolted into place to commemorate the completion of steel framing on the 1.85 million-square-foot stadium that broke ground in April.
Santa Clara Mayor Jamie Matthews and San Francisco 49ers Chief Executive Officer Jed York headlined the pre-topping ceremony, as the officials, executives and workers took turns using Sharpie felt pens to sign the beams.
"What a great day for history here in Santa Clara, a truly great project," Matthews said.
"We are going to keep working, we are looking forward to the next milestone," York said.
The stadium, to hold 68,500 fans, including 9,000 club seats and 165 luxury boxes, is now about 90 percent complete, with the concrete work, seating and other internal parts of the stadium to go before it's ready for the 49ers' pre-season games in 2014, York said.
The topping out is a milestone in the NFL team's move from its current home at aging Candlestick Park in San Francisco 45 miles south to Tasman Drive in Santa Clara, York said.
"This is going to be almost three times the size of Candlestick," York said. "We want to this to be the best outdoor entertainment experience."
York, noting the planned stadium's location within the Silicon Valley technology industry corridor, described ambitious plans for a "software-driven stadium," where fans use their smartphones during games for things like watching instant replays and making cashless payments for food and drinks at concession stands.
"It's more than just building an app," York said. "It's watching plays from different camera angles from your phone, the (NFL game replay) RedZone channel on your screen, fantasy football. You want fans to choose. You want 60,000 different experiences in this stadium."
York, who mentioned that the Bay Area has not hosted the Super Bowl NFL championship game since 1985 at Stanford Stadium, said NFL team owners are to meet in May to consider the 49ers' bid for the Super Bowl in 2016, in competition with the Miami Dolphin's planned South Florida stadium.
The 49ers also are in talks to rent out the stadium for college football and international soccer games as well as large concerts and music festivals with multiple stages.
During an interview after the ceremony, Matthews pointed out that Santa Clara, which owns the land under the facility and is leasing it to the 49ers for 40 years, would reap tax and other benefits for decades despite only a small investment on its part.
"We have less than $40 million invested in a $1.2 billion stadium," Matthews said. "We'll have the largest ATM machine that has ever been made in Silicon Valley."
Matthews then shared a chuckle with Larry Stone, the Santa Clara County assessor, who said that he'll be ready come January to assess the value of the unfinished stadium for property taxes, to be charged to the 49ers each year before and after the stadium opens.
Even though the NFL team is leasing the land from the city, "they are not exempt from taxation," Stone said.
Matthews, who noted that the 40-year lease is a long one, praised Candlestick Park for lasting as long at it has as a location for professional sports since 1960, and the 49ers' home stadium since 1971.
"These places don't last as long as ancient Rome," he said.