Tens of thousands of people are expected to converge on San Francisco this week for the annual Dreamforce conference.
The event, held by tech giant Salesforce, kicks off Monday.
On Sunday night, San Francisco police already were closing off some streets. The conference, which takes place at multiple venues, including Moscone Center, is expected to draw more than 170,000 people, plus another 10 million viewers online.
Notable conference guests include former first lady Michelle Obama, actor Ashton Kutcher and musical artist will.i.am.
Part of the Dreamforce festivities include a concert at AT&T Park on Tuesday night, featuring Lenny Kravitz and Alicia Keys.
The conference runs through Thursday.