The Gateway Arch is structurally sound, just a bit dirty, according to a report cited by the St. Louis Post-Dispatch.
Yet stains on the Arch caused by residue accumulation and graffiti aren't expected to be cleaned up anytime soon. An overall cleaning of the monument isn't feasible, a National Park Service official said.
According to the Post-Dispatch, officials have said that they're happy with the overall appearance of the Arch and recommend increased security at the base of the monument in hopes of preventing new graffiti.
Workers rappelled down the side of the Arch last October to sample the stains.
The Arch has never been cleaned, the Post-Dispatch reported.