The City rolled out the red carpet for Silicon Valley giant Oracle on Thursday, closing an entire city block through Nov. 17.
The closure is to accommodate the more than 40,000 people expected to arrive at the Moscone Center for Oracle OpenWorld, a technology and computer-engineering convention.
Howard Street will be closed between Third and Fourth streets.
Detour signs are in place near the convention site, and Caltrans message boards are placed on major freeways.
San Francisco Municipal Transit Agency spokeswoman Maggie Lynch advised motorists to avoid the area completely or take public transportation. She said the congestion is expected to be at its worst between 7 a.m. and 8 p.m.
Motorists traveling westbound on Howard Street will be detoured south on Second Street, and commuters driving north of Market Street will be directed down a maze of streets: from New Montgomery Street to Howard Street, back up Third Street and around Mission Street.
The convention is expected to occupy the three main centers at Moscone Center, as well as the street space between the centers where the company plans to put up tents.
Although the closures will be in place between Thursday and Nov. 17, the bulk of the convention is taking place between Sunday and Nov. 15.