Brokers contacted by GlobeSt.com were not able to confirm or deny the rumors but reports claim that the tower has been for sale for a number of weeks. It is unclear what the asking price is, but recent sales of office towers here--such as 1 Federal St., which was just sold for $375 million--ensure that the building will command an impressive price. Unconfirmed reports place the possible sale of the tower at $680 million.Among the factors that make International Place, which was developed by local developers Donald Chiofaro and Ted Oatis, extremely appealing to investors right now, despite an uncertain economy, is its close proximity along the Central Artery, which is going underground as part of the Big Dig.