The skyline of Boston’s Back Bay district showcases two of its tallest skyscrapers. The blue glass building in the center is Hancock Place, also called the John Hancock Tower. Since it was built in 1976 it has dominated the horizon at 790 feet. On the left is the second tallest high-rise in Bean Town. The Prudential Tower is 749 feet and was finished in 1964. The Back Bay derives its name from when it was a marshy bay before being filled with gravel during a massive landfill project which started in the mid-1850s.