And another Twitter user wrote: "Saw this motorcade going through London earlier (including JFK!) Assume it is something to do with the #USElection?"
However, some have speculated that the tour may in fact have been a publicity stunt to promote a new TV series based on Stephen King's book 11.22.63, starring James Franco.
But not everyone was pleased to see the motorcade, with some saying the stunt was in poor taste.
Liz Jordan tweeted: "Why is JFK and Jackie O's 'assassination' cavalcade driving around London? Tasteless whatever the reason."