Colonel Robert McCormick, eccentric owner of the Chicago Tribune in the early 1900s, collected – and asked his reporters to send – rocks from famous buildings and monuments around the world. He stockpiled pieces of the Taj Mahal, Westminster Abbey, the Great Pyramid and 140 or so others, which are now embedded around the tower’s base.
The unusual ‘bricks’ are all marked and viewable from street level. And the tradition continues: a twisted piece from the World Trade Center wreckage is one of the more recent additions.