51.   The south tower collapsed less than an hour later.

52.   The second tower had just collapsed.

53.   The south tower was collapsing.

54.   The Trade Center towers collapsed to the ground around and on top of the downed jets.

55.   Then, the other tower collapsed, and he was left on his own.

56.   These are the only taxes paid by many of the restaurant workers, maintenance staff and other low-income people killed when the towers collapsed.

57.   Then, last November, the incomplete, four-tier tower of logs collapsed.

58.   Then, the twin towers collapsed, and the most popular topics suddenly became Nostradamus, World Trade Center and Osama bin Laden.

59.   When the other tower collapsed, he and others rushed around a corner.

60.   When the twin towers collapsed, she posted a flier with a picture of her husband being hugged tightly by his children.