The nation's oldest and most venerated public park, Boston Common has belonged to the people of Boston since 1634. Throughout its history, it has been a centerpiece of civic life; the scene of executions, sermons, protests, and celebrations; and in each century, host to famous visitors from Generals Washington and Lafayette to Rev. Martin Luther King Jr. and Pope John Paul II. In Colonial times, it served as a meeting place, pasture, and military training field. Bostonians in the 19th century added treelined malls and paths and, following the Civil War, monuments and fountains. However, for...