11-11-2007 Center City Philadelphia
The National Building at 13th and Cherry Streets was reduced to rubble Sunday morning.
The areas between Broad and Race Streets and 12th and Filbert were closed down as the scheduled implosion took place at about 7:36 a.m.
Onlookers cheered as smoke filled the sky.
The demolition of the building will help make way for a $700 million expansion of the Pennsylvania Convention Center.
A new glass and steel pavilion will be built and stretch all the way to Broad Street. Once completed, it will be the largest connected exhibit space in the northeast with 541,000 square feet.
It will also be home to a 60,000 square foot ballroom, the grandest on the East coast.