From the Presidential Inaugural Committee (PIC) for those attending in person:
“Tickets are not required to view the swearing-in ceremony from the National Mall. Ticketing information for the ceremonial swearing-in is handled by the Joint Congressional Committee on Inaugural Ceremonies (JCCIC) here.
The ceremony will begin at 11:30 a.m., but we [PIC] recommend arriving as early as possible as both ticketed and non-ticketed areas are first-come, first-served.Please be prepared to be outside for a long period of time and dress warmly. A limited amount of food and beverage vendors may be available, but attendees are encouraged to bring snacks and beverages in order to stay healthy and hydrated.
If you are attending the Swearing-In ceremony and have a ticket, please follow the instructions provided with your admission ticket. Entrance will only be granted at the gate indicated on your admission ticket.
The non-ticketed area of the National Mall begins at 4th Street NW.”
Full version of the map: