Crew members scale St. Louis' Gateway Arch

ST. LOUIS (KGO) -- Crew members scaled St. Louis' Gateway Arch to wash it and get samples of discolored areas to check for corrosion.

Videos provided by the National Park Service of the workers in action were shot with GoPro cameras mounted to the helmets of the arch walkers.

At 630 feet above the city, it's a nerve-racking job but someone has to do it.