Professional climbers will rappel down all four sides of the Washington Monument tomorrow to get a closer look at any exterior damage caused by the 5.8 magnitude earthquake that shook D.C in late August.

The project is part of the National Park Service’s ongoing damage assessment. Today, the government agency released videos of the observation deck filmed during the earthquake. The footage shows the violent shaking visitors experienced near the top of the 555-foot high monument.

For a thorough survey of damage to the monument’s exterior, ropes will be anchored from an access hatch near the top of the monument, said Brandon Latham, a climbing ranger from Denali National Park, Alaska. Climbers will then crawl out windows at the observation deck, and head upwards to the access hatch to complete a top-to-bottom survey.

While the project sounds like something out of a spy movie, it’s not an uncommon move. The project team handling the survey has rappelled down a 220-foot obelisk in New Jersey, numerous state capitols, and buildings that are about the same height as the Washington Monument.

The climbers will be looking for any cracks, as well as small rocks that may have come loose during the earthquake and are still hanging onto the monument’s stone slabs. Such rock fragments, called spalls, have already been removed from inside the Washington Monument, said Jennifer Talken-Spaulding, of the National Park Service.

The agency says the monument’s elevator cables, damaged during the earthquake, will be replaced. The elevator was at level zero when the earthquake struck. Once the climbers and surveyors have pored over the exterior of the monument, the National Park Service said it will cover all open joints and cracks to prevent further weather damage. At the moment, said Bob Vogel, superintendent of the National Mall, a “substantial amount of water” is getting into the monument because of cracks and damaged joints missing mortar.

The park service did not give a date for when the monument will be open to visitors, adding that it will be in a better position in mid-October to estimate a re-opening date.