My mistake saying January 21. The Inauguration is supposed to be on January 20 per the Constitution, Amendment XX. https://www.archives.gov/founding-docs/amendments-11-27
There appear to be crowds much further west on the Mall towards the Washington Monument, there is some sort of flag display and something indiscernable beyond that.
I went back and checked it and it said Jan 19. I am not going to try to explain it. I think its an error by Alamy Live news.