Comcast on Monday said it signed a lease to move its headquarters to a $435 million 57-story office building that will be built in downtown Philadelphia.

As part of the deal the cable titan signed a 15%BD;-year lease with Liberty Property Trust to occupy around 44 percent of the new building, which will be called Comcast Center. That translates into around 534,000 square feet on 24 floors and establish Comcast as the anchor tenant in the building, which is expected to be completed by fall 2007.

The building, located at 1701 John F. Kennedy Blvd., will be Philadelphia’s tallest building at 975 feet.