San Francisco recently did something it hasn't done in a century: flipped the switch on giant lights blazing the year "1915" on the tower of its landmark Ferry Building.
The numbers mark the centennial of the Panama–Pacific International Exposition.
The lights that went live Tuesday are new, but they look like the ones 19 million visitors would have seen on the Ferry Building when they came to see the expo.
The 1915 lights appear on both sides of the tower and will remain until Dec. 4, the day the expo ended. (The building has since become a popular waterfront marketplace at the end of Market Street.)
The city's year-long centennial celebration began Feb. 20 to coincide with the opening of the expo on Feb. 20, 1915.
The numbers are almost 27 feet wide and 12 feet high, and use 1,100 LED bulbs, according to a statement from the PPIE100 consortium, which has been raising funds and planning centennial events year-round in the city.
The only original building still standing, the Palace of Fine Arts, was reopened in December as part of the events. It remains open all year as what's called Innovation Hangar, a place to see new inventions, prototypes and exhibitions.
The 1915 exposition was a major coup for San Francisco, an event that not only celebrated the high-tech accomplishment of its day -- the Panama Canal -- but also showed the world that San Francisco had bounced back from the devastating 1906 earthquake.
To understand the importance of the exposition, visit "City Rising: San Francisco and the 1915 World's Fair" at the California Historical Society at 678 Mission St.