Sarah Bourne captured Air Force One at Logan shortly before 3 p.m.
About 15 minutes later, David Finnerty spotted his motorcade on the other side of the harbor:
And not long after that, Neal Gaffey watched him exit his limo at Faneuil Hall.
UPDATE: After his speech, the president shut the turnpike and the neighboring Worcester Line for a ride to a fundraiser in Weston. Michael captured the motorcade near BU: