Engineers are evaluating the Washington Monument just over a month after a 5.8 magnitude earthquake shook the East Coast, Aug. 23.
Workers will rappel down the sides of the structure Tuesday to check for cracks and other damage.
"The heaviest damage appears to be concentrated at the very top of the monument, in what is called the pyramidion, where large cracks of up to 1 1/4 inch wide developed through stone and mortar joints," Bob Vogel, superintendent of the National Mall and Memorial Parks, told CNN.
The news comes as new footage was released of tourists fleeing down the steps of the building during the earthquake.
Although Vogel said the monument is structurally sound, the national landmark will remain closed indefinitely.
"It is a testament to the original builders that the monument has withstood not just this earthquake, but an even larger one in the late 1800s," he said.