London Day Trip from Paris by Eurostar. Day trip from Paris to London on the Eurostar. Take the high-speed train to London for an easy day trip. See top London attractions on a narrated hop-on hop-off sightseeing tour. Visit Buckingham Palace, Big Ben, Westminster Abbey, the Tower of London and more. Enjoy a relaxing Thames River cruise. Spend up to eight hours in London before the train ride back to Paris. Book this Trip and Save 22%: London Day Trip from Paris by Eurostar.