Workers scale Arch in search of stains

Engineers with Wiss, Janney, Elstner Associates, Inc., of Chicago, make their way down the north leg of the Gateway Arch, Thursday, Oct. 16, 2014, in St. Louis, Mo., as they attempt to get samples of staining on the aging monument. The National Park service is hoping to sample the stains and figure out what caused them so they can be removed. (AP Photo/St. Louis Post-Dispatch, Christian Gooden)
Engineers with Wiss, Janney, Elstner Associates, Inc., of Chicago, make their way down the north leg of the Gateway Arch, Thursday, Oct. 16, 2014, in St. Louis, Mo., as they attempt to get samples of staining on the aging monument. The National Park service is hoping to sample the stains and figure out what caused them so they can be removed. (AP Photo/St. Louis Post-Dispatch, Christian Gooden)

ST. LOUIS (AP) - Tourists, commuters and downtown office workers are enjoying an unusual view of the Gateway Arch Thursday as a group of workers climb the iconic landmark in search of stains.

Workers could be seen rappelling down the Arch in a repair project commissioned by the National Park Service.

The Arch remains open, but public access to portions of its surrounding grounds is limited to the south entrance.