About 20 miles west of London, the meadow of Runnymede hosts a memorial to John F. Kennedy, dedicated by Queen Elizabeth II two years after the U.S. president’s assassination on Nov. 22, 1963. Situated on land bequeathed in perpetuity to the American people, the memorial overlooks the riverbank where the Magna Carta — a pivotal document prefiguring modern constitutional democracies — was sealed 800 years before. It’s an apt place for visitors to reflect on President Kennedy’s legacy of democratic leadership and service. Across the Atlantic, the MIT campus hosts…