The Prudential Tower, also known as the Prudential Building or, colloquially, The Pru, is an International Style skyscraper in Boston, Massachusetts. The building, a part of the Prudential Center complex, currently stands as the 2nd-tallest building in Boston, behind the  200 Clarendon building. The Prudential Tower was designed by Charles Luckman and Associates for Prudential Insurance. Completed in 1964, the building is tall, with 52 floors. It contains of commercial and retail space. Including its radio mast, the tower stands as the tallest building in Boston and is tied with others as the 77th-tallest in the United States, rising to in height. A 50th-floor observation deck, called the Skywalk Observatory, is currently the highest observation deck in New England open to the public, as the higher observation deck of the John Hancock Tower has been closed since the terror attacks of September 11, 2001. A restaurant, the Top of the Hub, occupies the 52nd floor.