File:Brooks Hall SF underground 1958-04-01.jpg

The main underground hall of Brooks Hall, San Francisco's first modern convention center, nears completion on April 1, 1958. It would open on April 11, 1958 and later host the first Macworld Conference & Expo in February 1985.

Source

 * SF’s Brooks Hall: Mayor made a mountain out of Mole Hall moniker by Bill Van Niekerken, San Francisco Chronicle. 2018-01-30.