the name is a variation of one of the original appellations of the city, "trimountaine", a reference to a hill that formerly had three peaks. beacon hill, with its single peak, is all that remains of the trimountain. much of the trimountain was removed, and the earth used as fill to expand the shawmut peninsula. the two smaller peaks, cotton hill (or pemberton hill, at what is now pemberton square) and mt. whoredom (or mt. vernon, formerly at the location of the modern-day louisburg square) no longer exist. the central peak, sentry hill, now called beacon hill, is smaller than the original peak, which reached approximately to the height of the top of the state house.