Serving as the headquarters of the Mason's Grand Lodge of Pennsylvania, and designated a National Historic Landmark, the temple is one of the nation's most elaborate examples of Masonic architecture. It features the Masonic Library and Museum of Pennsylvania. The Museum's collection consists of more than 30,000 items, including George Washington's Masonic Apron, two letters in Washington's own hand addressed to his Masonic brethren; and Benjamin Franklin's Masonic Sash.